lightning: specify collation when parquet value to string datum (#38391)

[ti-chi-bot]

This is an automated cherry-pick of #38391

What problem does this PR solve?

Issue Number: close #38351

Problem Summary:

What is changed and how it works?

For parquet parser, when setting a value into the string datum, use the "utf8mb4_bin" collation instead of an empty collation. This will make the string conversion logic not report errors, thus improving the performance.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

Please refer to Release Notes Language Style Guide to write a quality release note.

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• dsdashun

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[ti-chi-bot]

@ti-chi-bot: This cherry pick PR is for a release branch and has not yet been approved by release team.
Adding the do-not-merge/cherry-pick-not-approved label.

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[dsdashun]

LGTM

[dsdashun]

/cc @lance6716

[lance6716]

6.3 will not release a patch version

[ti-chi-bot]

@ti-chi-bot: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
idc-jenkins-ci-tidb/check_dev_2	7e71d45	link	true	/test check-dev2
idc-jenkins-ci-tidb/mysql-test	7e71d45	link	true	/test mysql-test

Full PR test history. Your PR dashboard.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository. I understand the commands that are listed here.