lightning: cherry-pick some PRs (#1458)

[ti-chi-bot]

What problem does this PR solve?

cherry-pick pingcap/tidb#27769

also cherry-pick pingcap/tidb#29730 to pass integration test

also partically cherry-pick pingcap/tidb#29062 to fix some unstable integration tests

What is changed and how it works?

Check List

Tests

• Unit test

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

Release note

• Fix the bug that import from s3 may fail if the csv file size is similar to region-split-size(default is 256MiB).

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• glorv
• gozssky

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[glorv]

/build

[glorv]

/cc @zhouqiang-cl PTAL

[ti-chi-bot]

@glorv: GitHub didn't allow me to request PR reviews from the following users: PTAL.

Note that only pingcap members and repo collaborators can review this PR, and authors cannot review their own PRs.

In response to this:

/cc @zhouqiang-cl PTAL

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[glorv]

/merge

[ti-chi-bot]

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

Commit hash: 7a935d5

[glorv]

/run-all-tests