ddl: validate the placement policy constraint when create it

[AilinKid]

Signed-off-by: ailinkid 314806019@qq.com

What problem does this PR solve?

Issue Number: partial close #26580

What is changed and how it works?

What's Changed:
when create placement policy name ???_constraints=string, constraints=string, the common constraints is actually appended to the previous constraints. This way, we will check the compatibility for the merge of them.

Check List

Tests

• Unit test
• Integration test

Documentation

• Affects user behaviors

Release note

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• morgo
• xhebox

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[xhebox]

/merge

[ti-chi-bot]

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

Commit hash: 1783fb1

[ti-chi-bot]

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