infoschema: try on each PD member until one succeeds or all fail (#35285)

[ti-srebot]

cherry-pick #35285 to release-6.1
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/35508

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

git push git@github.com:ti-srebot/tidb.git pr/35508:release-6.1-7bd892340dd1

---

Signed-off-by: JmPotato ghzpotato@gmail.com

What problem does this PR solve?

Issue Number: close #35268.

What is changed and how it works?

GetPDServerInfo will try on each PD member until one succeeds or all fail.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)

Before:

After:

Release note

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• nolouch
• tiancaiamao

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[ti-srebot]

/run-all-tests

[ti-srebot]

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

[sre-bot]

Code Coverage Details: https://codecov.io/github/pingcap/tidb/commit/ab2bdb52bd210a052bc8dcb9e1ccd01268044a7a

[bb7133]

/merge

[ti-chi-bot]

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

Commit hash: b2e0f58