Fix Context returned from LockShard

[GuptaManan100]

Description

This PR fixes the context returned from LockShard. As described in #15925, we aren't sending the correct context back from LockShard. This PR fixes this problem.

Related Issue(s)

• Bug Report: LockShard returns a context without a timeout #15925

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

[vitess-bot]

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Backward compatibility

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Walking through code with Manan, we may need more changes.