planner: fix the unstable unit test TestAnalyzeIncremental (#26460)

[ti-srebot]

cherry-pick #26460 to release-4.0
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/26498

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

git push git@github.com:ti-srebot/tidb.git pr/26498:release-4.0-95a40ac3d411

---

What problem does this PR solve?

Issue Number: close #25013

Problem Summary: planner: fix the unstable unit test TestAnalyzeIncremental

Check List

Tests

• Unit test

Release note

• No release note

[ti-chi-bot]

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[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.

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[ti-srebot]

/run-all-tests

[ti-srebot]

@qw4990 you're already a collaborator in bot's repo.

[xhebox]

close for DMR version