syncer(dm): fix collation compatibility behaviour

[lance6716]

Signed-off-by: lance6716 [email protected]

What problem does this PR solve?

Issue Number: close #6832

What is changed and how it works?

Check List

Tests

• Unit test

Questions

Will it cause performance regression or break compatibility?

Do you need to update user documentation, design documentation or monitoring documentation?

Release note

Fix when use "strict" collation_compatible, DM sometimes generate SQL with duplicated collation

[ti-chi-bot]

[REVIEW NOTIFICATION]

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• WizardXiao

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[lance6716]

/cc @lichunzhu @WizardXiao

[lance6716]

/check-issue-triage-complete
/run-verify

[codecov-commenter]

Codecov Report

Merging #6833 (5ce08c0) into master (435053b) will increase coverage by 0.5196%.
The diff coverage is 69.9570%.

Flag	Coverage Δ
cdc	67.3777% <71.9101%> (+1.2999%)	⬆️
dm	52.0413% <50.0000%> (+0.0350%)	⬆️
engine	62.7225% <0.0000%> (-0.3039%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

@@               Coverage Diff                @@
##             master      #6833        +/-   ##
================================================
+ Coverage   59.4341%   59.9537%   +0.5196%     
================================================
  Files           787        784         -3     
  Lines         89743      89534       -209     
================================================
+ Hits          53338      53679       +341     
+ Misses        31702      31156       -546     
+ Partials       4703       4699         -4     

[lance6716]

/cc @GMHDBJD

[lance6716]

/merge

[ti-chi-bot]

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

Commit hash: cb687db

[ti-chi-bot]

@lance6716: Your PR was out of date, I have automatically updated it for you.

At the same time I will also trigger all tests for you:

/run-all-tests

If the CI test fails, you just re-trigger the test that failed and the bot will merge the PR for you after the CI passes.

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[lance6716]

/run-verify

[lance6716]

/run-verify

[ti-chi-bot]

In response to a cherrypick label: new pull request created: #6846.