functions: fix some string function has wrong collation and flag (#23835)

[ti-srebot]

cherry-pick #23835 to release-5.0
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git pr https://github.com/pingcap/tidb/pull/23879

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---

What problem does this PR solve?

Issue Number: close #23759

some string functions get the wrong binary flag result, the returned value has a binary flag only its return value is binary charset

Check List

Tests

• Unit test

Release note

• fix some string function get wrong result

[ti-srebot]

/run-all-tests

[ti-srebot]

@xiongjiwei you're already a collaborator in bot's repo.

[xiongjiwei]

/run-unit-test

[wshwsh12]

LGTM

[wjhuang2016]

/lgtm

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• wjhuang2016
• wshwsh12

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[xiongjiwei]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 4b6439c

[zimulala]

/run-uint-test

[ti-chi-bot]

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