[Bug] Fix the bug of nullif function:

[HappenLee]

Proposed changes

1. Prevent return NULL call nullif(98, null) in FE
2. Support DecimalV2 of nullif function to get the right result

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• Bugfix (non-breaking change which fixes an issue)
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Checklist

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• I have created an issue on (Fix [BUG] NULLIF() function result is wrong #5858) and described the bug/feature there in detail
• Compiling and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
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[EmmyMiao87]

what if SELECT ALL NULLIF (-98, NULL) AS col0 ?

[HappenLee]

what if SELECT ALL NULLIF (-98, NULL) AS col0 ?

The right result of nullif(-98, null) is -98. but before fix the bug, the answer is null. Because the FE wiil treat all the function not in non_null_result_with_null_param_functions alwalys null if there params have null.

so add the nullif function to non_null_result_with_null_param_functions we can get the right answer:98

[EmmyMiao87]

non_null_result_with_null_param_functions

Great

[EmmyMiao87]

LGTM