Optimize the performance of bidirectional synchronous update table of _drainer_repl_mark (#903)

[sre-bot]

cherry-pick #903 to release-3.0

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…of _drainer_repl_mark

What problem does this PR solve?

1.Optimize the performance of bidirectional synchronous update table of _drainer_repl_mark

What is changed and how it works?

The number of channel related records in the mark table is initialized according to the number of worker "count. During synchronization, each syncer operates one piece of data, which will not cause multithreading to update one record, resulting in synchronization performance bottleneck

Check List

Tests

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

Code changes

• Has exported function/method change
• Has exported variable/fields change
• Has interface methods change
• Has persistent data change

Side effects

• Possible performance regression
• Increased code complexity
• Breaking backward compatibility

Related changes

• Need to cherry-pick to the release branch
• Need to update the documentation
• Need to update the tidb-ansible repository
• Need to be included in the release note

[WangXiangUSTC]

LGTM

[sre-bot]

/run-all-tests