expression: adjust DST for convert_tz() (#37206)

[ti-srebot]

cherry-pick #37206 to release-5.1
You can switch your code base to this Pull Request by using git-extras:

# In tidb repo:
git pr https://github.com/pingcap/tidb/pull/37950

After apply modifications, you can push your change to this PR via:

git push git@github.com:ti-srebot/tidb.git pr/37950:release-5.1-8d5328ec4e84

---

What problem does this PR solve?

Issue Number: close #30081

Problem Summary:

There is a similar issue #28739.

What is changed and how it works?

I used AdjustGoTime introduced in #30405 for convert_tz().

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]

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[ti-chi-bot]

@ti-srebot: 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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[ti-srebot]

/run-all-tests

[VelocityLight]

This pull request is closed because it's related version has closed automatic cherry-picking.
If it's still needed, you can reopen it or just regenerate it using bot,
see:

• https://prow.tidb.io/command-help#cherrypick
• https://book.prow.tidb.net/#/plugins/cherrypicker

You can find more details at:

• https://internals.tidb.io/t/topic/785