kvclient(ticdc): close the grpc client after all goroutine exited to prevent data race and panic (#10865)

[ti-chi-bot]

This is an automated cherry-pick of #10865

What problem does this PR solve?

Issue Number: close #10799

What is changed and how it works?

• use errgroup context to control grpc stream, to make it can be canceld.
• do not set the grpc stream to nil after CloseSend

Check List

Tests

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

Questions

Will it cause performance regression or break compatibility?

Do you need to update user documentation, design documentation or monitoring documentation?

Release note

`None`

[3AceShowHand]

/retest

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: 3AceShowHand

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [3AceShowHand]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[3AceShowHand]

/retest