copr: fix error when cast const Enum to any type (#14149)

[ti-chi-bot]

This is an automated cherry-pick of #14149

What is changed and how it works?

Issue Number: Close #14156
Close pingcap/tidb#40341

What's Changed:
Make is_expr_eval_to_scalar can identifie const Enum.

copr: fix error when cast const Enum to any type

Related changes

• PR to update pingcap/docs/pingcap/docs-cn:
• Need to cherry-pick to the release branch

Check List

Tests

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

Side effects

• Performance regression
  • Consumes more CPU
  • Consumes more MEM
• Breaking backward compatibility

Release note

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[ti-chi-bot]

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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.
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[ti-chi-bot]

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