Increase health check channel buffer (#17821)

[makinje16]

Description

This PR backports vitessio#17821 as it solves an vitessio#17629 in which vtgate buffering would time out after receiving a healthcheck from a new primary.

Related Issue(s)

vitessio#17629

Checklist

• "Backport to:" labels have been added if this change should be back-ported to release branches
• If this change is to be back-ported to previous releases, a justification is included in the PR description
• Tests were added or are not required
• Did the new or modified tests pass consistently locally and on CI?
• Documentation was added or is not required

Deployment Notes

[github-actions]

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[github-actions]

This PR was closed because it has been stale for 7 days with no activity.