[optimize](count) optimize key exact query without reading data

[zzzxl1993]

Proposed changes

#28494

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...

[zzzxl1993]

run buildall

[github-actions]

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

[zzzxl1993]

run buildall

[github-actions]

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

[doris-robot]

TeamCity be ut coverage result:
Function Coverage: 37.75% (7993/21171)
Line Coverage: 29.45% (64936/220460)
Region Coverage: 28.92% (33404/115487)
Branch Coverage: 24.79% (17136/69120)
Coverage Report: http://coverage.selectdb-in.cc/coverage/b8fd7b0f6c3a2619f64264c9e70fc3e1d235f4eb_b8fd7b0f6c3a2619f64264c9e70fc3e1d235f4eb/report/index.html

[doris-robot]

(From new machine)TeamCity pipeline, clickbench performance test result:
the sum of best hot time: 49.19 seconds
stream load tsv: 569 seconds loaded 74807831229 Bytes, about 125 MB/s
stream load json: 19 seconds loaded 2358488459 Bytes, about 118 MB/s
stream load orc: 65 seconds loaded 1101869774 Bytes, about 16 MB/s
stream load parquet: 31 seconds loaded 861443392 Bytes, about 26 MB/s
insert into select: 30.3 seconds inserted 10000000 Rows, about 330K ops/s
storage size: 17162530655 Bytes