lightning: add back table empty check and add a switch config (#30887)

[ti-srebot]

cherry-pick #30887 to release-5.2
You can switch your code base to this Pull Request by using git-extras:

# In tidb repo:
git pr https://github.com/pingcap/tidb/pull/33881

After apply modifications, you can push your change to this PR via:

git push git@github.com:ti-srebot/tidb.git pr/33881:release-5.2-393415782452

---

What problem does this PR solve?

Issue Number: close #27919

Problem Summary:

What is changed and how it works?

• Add a new config tikv-importer.incremental-import to control whether allow lightning to import to table that already contains data
• When tikv-importer.incremental-import = false, tidb-lightning will check target tables' vacancy. If the tables already contains data, lightning will directly report an error and exit. In this mode, lightning will also avoid create and write data into lightning_meta in target tidb.

Check List

Tests

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

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility
  • Add a new config to control the table empty check, so this is not compatible with v5.2 and v5.3.

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

Add a new config to control whether support incremental import.

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• glorv

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[ti-srebot]

/run-all-tests

[ti-srebot]

@glorv you're already a collaborator in bot's repo.

[sre-bot]

Code Coverage Details: https://codecov.io/github/pingcap/tidb/commit/b54887173a492f419c00682c32e31fcd400393ee

[glorv]

@kennytm @gozssky PTAL

[sleepymole]

lint error

[](https://ci.pingcap.net/blue/organizations/jenkins/tidb_ghpr_check/detail/tidb_ghpr_check/58657/pipeline#step-113-log-154)[2022-04-12T08:51:46.852Z] br/pkg/lightning/restore/check_info.go

[2022-04-12T08:51:46.852Z] make: *** [fmt] Error 1

[glorv]

/run-unit-test

[glorv]

/run-mysql-test

[glorv]

@gozssky PTAL again

[sleepymole]

Integration test fail. I'm not sure if it is caused by this PR.
https://ci.pingcap.net/job/br_ghpr_unit_and_integration_test/11159/display/redirect

[sleepymole]

/run-integration-br-test

[ti-chi-bot]

@ti-srebot: This cherry pick PR is for a release branch and has not yet been approved by release team.
Adding the do-not-merge/cherry-pick-not-approved label.

To merge this cherry pick, it must first be approved by the collaborators.

AFTER it has been approved by collaborators, please ping the release team in a comment to request a cherry pick review.

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[VelocityLight]

This pull request is closed because it's related version has closed automatic cherry-picking.
If it's still needed, you can reopen it or just regenerate it using bot,
see:

• https://prow.tidb.io/command-help#cherrypick
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• https://internals.tidb.io/t/topic/785