dump: always split TiDB v4.* tables through tidb rowid to save TiDB's memory (#273)

[ti-chi-bot]

This is an automated cherry-pick of #273

What problem does this PR solve?

fix #104 and close #278

What is changed and how it works?

Split chunks by PKIsHandle for TiDB v4.0.*. Make sure TiDB won't OOM through splitting tables by rowids.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
  Test dump with v4.0.0. The result is looks expected.

Related changes

• Need to cherry-pick to the release branch

Release note

• Always split TiDB v4.* tables through tidb rowid to save TiDB's memory.

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• lance6716

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[lichunzhu]

/merge

[ti-chi-bot]

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

Commit hash: 33997cb

[lonng]

/label cherry-pick-approved