[Enhancement] Reduct the unnecessary ALWAYS_NULLABLE in nullable mode

[zclllyybb]

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• I had searched in the issues and found no similar issues.

Description

for many doris' functions, they have nullable mode ALWAYS_NULLABLE but in fact no need to be. many of them could be changed to DEPEND_ON_ARGUMENT or CUSTOM just like #27343, #22321 and #26827.

Solution

It may relate to 3 position: BE's function's implementation, function prototype of Nereids planner and function prototype of Legacy planner.
If could reduct it, reduct it.

Are you willing to submit PR?

• Yes I am willing to submit a PR!

Code of Conduct

• I agree to follow this project's Code of Conduct

[koarz]

l want try

[zclllyybb]

l want try

sure! u can add my wechat torch-wood_ for more information