client: avoid to add redundant grpc metadata (#7471)

[ti-chi-bot]

This is an automated cherry-pick of #7471

What problem does this PR solve?

Issue Number: Close #7469

What is changed and how does it work?

Check List

Tests

• Manual test (add detailed scripts or steps below)
  

Code changes

• Has the configuration change
• Has HTTP API interfaces changed (Don't forget to add the declarative for the new API)
• Has persistent data change

Side effects

• Possible performance regression
• Increased code complexity
• Breaking backward compatibility

Related changes

• PR to update pingcap/docs/pingcap/docs-cn:
• PR to update pingcap/tiup:
• Need to cherry-pick to the release branch

Release note

None.

[ti-chi-bot]

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[ti-chi-bot]

This cherry pick PR is for a release branch and has not yet been approved by triage owners.
Adding the do-not-merge/cherry-pick-not-approved label.

To merge this cherry pick:

1. It must be approved by the approvers firstly.
2. AFTER it has been approved by approvers, please wait for the cherry-pick merging approval from triage owners.

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[CabinfeverB]

It's enhancement, no need to cherry pick