codec: Don't convert set or enum datum to float64 (#32372)

[ti-srebot]

cherry-pick #32372 to release-5.3
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/32565

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

git push git@github.com:ti-srebot/tidb.git pr/32565:release-5.3-cc789d078b44

---

What problem does this PR solve?

Issue Number: close #32302

Problem Summary:

Missing part of #32308

What is changed and how it works?

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

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• MyonKeminta
• cfzjywxk

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[ti-srebot]

/run-all-tests

[ti-srebot]

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

[ekexium]

PTAL @cfzjywxk @MyonKeminta

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (release-5.3@62e62ff). Click here to learn what that means.
The diff coverage is n/a.

Additional details and impacted files

@@               Coverage Diff                @@
##             release-5.3     #32565   +/-   ##
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  Coverage               ?   53.3432%           
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  Files                  ?         19           
  Lines                  ?       3365           
  Branches               ?          0           
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  Hits                   ?       1795           
  Misses                 ?       1421           
  Partials               ?        149           

[ti-chi-bot]

This pull request is closed because its 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.net/command-help#cherrypick
https://book.prow.tidb.net/#/plugins/cherrypicker