branch-2.1: [fix](Nereids) fold constant for string function process emoji character by mistake #49087

[LiBinfeng-01]

pick: #49087
Related PR: #40441

Problem Summary:

wrong calculation of emoji character length in some String function when do constant folding in FE. For example:

select STRLEFT('😊😉👍', 2);

should return 😊😉, but fe return 😊 only when folding constant

fixed functions:

• left
• strleft
• right
• strright
• locate
• character_length
• split_by_string
• overlay
• replace_empty

What problem does this PR solve?

Issue Number: close #xxx

Related PR: #xxx

Problem Summary:

Release note

None

Check List (For Author)

• Test

  • Regression test
  • Unit Test
  • Manual test (add detailed scripts or steps below)
  • No need to test or manual test. Explain why:
    • This is a refactor/code format and no logic has been changed.
    • Previous test can cover this change.
    • No code files have been changed.
    • Other reason

• Behavior changed:

  • No.
  • Yes.

• Does this need documentation?

  • No.
  • Yes.

Check List (For Reviewer who merge this PR)

• Confirm the release note
• Confirm test cases
• Confirm document
• Add branch pick label

[Thearas]

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1. What problem was fixed (it's best to include specific error reporting information). How it was fixed.
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4. Which code was refactored and why was this part of the code refactored?
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[LiBinfeng-01]

run buildall

[LiBinfeng-01]

run buildall

[LiBinfeng-01]

run p0

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