[opt](scanner) optimize the number of threads of scanners, follow up #28640

[AshinGau]

Proposed changes

follow up #28640, doris_scanner_thread_pool_thread_num may be to large in machines with 128 cores.

Further comments

If this is a relatively large or complex change, kick off the discussion at dev@doris.apache.org by explaining why you chose the solution you did and what alternatives you considered, etc...

[AshinGau]

run buildall

[morningman]

LGTM

[github-actions]

PR approved by at least one committer and no changes requested.

[github-actions]

PR approved by anyone and no changes requested.

[github-actions]

clang-tidy review says "All clean, LGTM! 👍"

[doris-robot]

TeamCity be ut coverage result:
Function Coverage: 36.67% (8647/23579)
Line Coverage: 28.73% (70617/245754)
Region Coverage: 27.62% (36438/131919)
Branch Coverage: 24.34% (18643/76586)
Coverage Report: http://coverage.selectdb-in.cc/coverage/fb21d874fcd963520837f6ef03a6d2ecdf19179a_fb21d874fcd963520837f6ef03a6d2ecdf19179a/report/index.html

[doris-robot]

TPC-H: Total hot run time: 38978 ms

machine: 'aliyun_ecs.c7a.8xlarge_32C64G'
scripts: https://github.com/apache/doris/tree/master/tools/tpch-tools
Tpch sf100 test result on commit fb21d874fcd963520837f6ef03a6d2ecdf19179a, data reload: false

------ Round 1 ----------------------------------
q1	18692	5181	5129	5129
q2	2041	142	130	130
q3	10786	1153	1141	1141
q4	11361	752	859	752
q5	8289	3269	3173	3173
q6	213	126	127	126
q7	877	534	512	512
q8	9431	1922	1996	1922
q9	9052	6675	6482	6482
q10	8309	3115	3063	3063
q11	431	201	212	201
q12	355	201	195	195
q13	20170	3425	3323	3323
q14	239	213	218	213
q15	555	512	509	509
q16	477	411	382	382
q17	932	555	489	489
q18	7389	6875	6859	6859
q19	4357	1403	1389	1389
q20	581	311	286	286
q21	2702	2401	2413	2401
q22	342	319	301	301
Total cold run time: 117581 ms
Total hot run time: 38978 ms

----- Round 2, with runtime_filter_mode=off -----
q1	5497	5295	5184	5184
q2	324	213	216	213
q3	3344	3258	3140	3140
q4	2072	2063	2041	2041
q5	5985	5839	5914	5839
q6	193	117	116	116
q7	2305	1909	1831	1831
q8	3227	3363	3369	3363
q9	8941	8839	8829	8829
q10	3938	3764	3844	3764
q11	563	459	460	459
q12	778	652	640	640
q13	16943	3172	3142	3142
q14	293	265	264	264
q15	545	504	498	498
q16	529	469	488	469
q17	1862	1856	1840	1840
q18	9350	15062	9621	9621
q19	23724	1618	1549	1549
q20	4639	1945	1913	1913
q21	14956	5425	5491	5425
q22	1136	542	533	533
Total cold run time: 111144 ms
Total hot run time: 60673 ms

[doris-robot]

TPC-DS: Total hot run time: 177775 ms

machine: 'aliyun_ecs.c7a.8xlarge_32C64G'
scripts: https://github.com/apache/doris/tree/master/tools/tpcds-tools
TPC-DS sf100 test result on commit fb21d874fcd963520837f6ef03a6d2ecdf19179a, data reload: false

query1	937	329	328	328
query2	6546	1917	2018	1917
query3	6703	194	199	194
query4	34161	22103	22244	22103
query5	6890	614	530	530
query6	251	186	170	170
query7	4603	260	266	260
query8	221	188	185	185
query9	8385	2621	2585	2585
query10	431	250	241	241
query11	16724	15618	15561	15561
query12	127	67	72	67
query13	1678	400	384	384
query14	10459	6891	6946	6891
query15	211	180	182	180
query16	4606	237	239	237
query17	982	495	491	491
query18	1808	267	250	250
query19	179	136	135	135
query20	71	74	68	68
query21	190	132	135	132
query22	4909	4733	4666	4666
query23	31499	30910	31011	30910
query24	11787	2767	2826	2767
query25	571	313	312	312
query26	1606	144	146	144
query27	3225	274	272	272
query28	7186	1843	1835	1835
query29	1303	628	626	626
query30	285	144	142	142
query31	934	744	766	744
query32	71	50	48	48
query33	692	219	212	212
query34	1131	462	463	462
query35	879	777	791	777
query36	1448	1331	1330	1330
query37	96	59	60	59
query38	3371	3289	3244	3244
query39	1321	1292	1260	1260
query40	238	87	83	83
query41	37	33	34	33
query42	92	83	93	83
query43	558	492	513	492
query44	1065	690	703	690
query45	206	184	179	179
query46	1072	643	646	643
query47	1658	1524	1606	1524
query48	400	317	312	312
query49	1133	287	284	284
query50	673	313	309	309
query51	5329	5217	5225	5217
query52	91	80	79	79
query53	326	259	253	253
query54	873	447	444	444
query55	83	74	80	74
query56	179	164	176	164
query57	993	905	967	905
query58	192	167	166	166
query59	2932	2864	2781	2781
query60	217	188	184	184
query61	87	84	84	84
query62	658	398	390	390
query63	280	253	260	253
query64	5058	1831	1800	1800
query65	3354	3248	3247	3247
query66	1237	316	313	313
query67	15943	15315	15115	15115
query68	11395	526	542	526
query69	629	307	308	307
query70	1728	1563	1545	1545
query71	541	212	215	212
query72	5079	2864	2850	2850
query73	2406	313	317	313
query74	6906	6426	6408	6408
query75	4973	2330	2265	2265
query76	6132	1031	1013	1013
query77	665	240	250	240
query78	9112	8887	8754	8754
query79	1050	519	499	499
query80	579	331	319	319
query81	459	206	205	205
query82	202	81	82	81
query83	140	120	116	116
query84	274	71	69	69
query85	1057	324	316	316
query86	384	404	406	404
query87	3549	3315	3302	3302
query88	2799	2158	2159	2158
query89	442	364	369	364
query90	2002	190	184	184
query91	162	121	131	121
query92	51	46	48	46
query93	2116	435	427	427
query94	1201	168	159	159
query95	507	459	468	459
query96	642	311	310	310
query97	4233	4135	4136	4135
query98	207	200	182	182
query99	994	666	726	666
Total cold run time: 296057 ms
Total hot run time: 177775 ms

[doris-robot]

ClickBench: Total hot run time: 30.39 s

machine: 'aliyun_ecs.c7a.8xlarge_32C64G'
scripts: https://github.com/apache/doris/tree/master/tools/clickbench-tools
ClickBench test result on commit fb21d874fcd963520837f6ef03a6d2ecdf19179a, data reload: false

query1	0.03	0.03	0.03
query2	0.05	0.03	0.02
query3	0.23	0.06	0.05
query4	1.69	0.06	0.07
query5	0.53	0.53	0.52
query6	1.30	0.65	0.62
query7	0.02	0.01	0.01
query8	0.04	0.02	0.02
query9	0.53	0.50	0.50
query10	0.57	0.58	0.56
query11	0.11	0.09	0.08
query12	0.11	0.10	0.09
query13	0.60	0.60	0.60
query14	0.81	0.78	0.79
query15	0.80	0.78	0.77
query16	0.39	0.38	0.38
query17	1.03	1.00	1.03
query18	0.24	0.24	0.26
query19	1.74	1.81	1.77
query20	0.01	0.01	0.01
query21	15.43	0.57	0.57
query22	2.52	2.33	2.73
query23	17.32	0.86	0.71
query24	2.76	0.87	0.18
query25	0.31	0.18	0.12
query26	0.45	0.15	0.14
query27	0.08	0.05	0.04
query28	12.59	0.76	0.76
query29	12.52	3.12	3.17
query30	0.53	0.50	0.45
query31	2.80	0.35	0.35
query32	3.39	0.48	0.49
query33	3.24	3.24	3.26
query34	15.74	4.21	4.26
query35	4.28	4.27	4.24
query36	1.10	1.08	1.08
query37	0.06	0.05	0.05
query38	0.03	0.02	0.03
query39	0.03	0.01	0.01
query40	0.16	0.13	0.13
query41	0.07	0.02	0.02
query42	0.02	0.01	0.02
query43	0.02	0.02	0.02
Total cold run time: 106.28 s
Total hot run time: 30.39 s

[doris-robot]

Load test result on machine: 'aliyun_ecs.c7a.8xlarge_32C64G'

Load test result on commit fb21d874fcd963520837f6ef03a6d2ecdf19179a with default session variables
Stream load json:         19 seconds loaded 2358488459 Bytes, about 118 MB/s
Stream load orc:          58 seconds loaded 1101869774 Bytes, about 18 MB/s
Stream load parquet:      32 seconds loaded 861443392 Bytes, about 25 MB/s
Insert into select:       14.8 seconds inserted 10000000 Rows, about 675K ops/s