[core] Remove client call tag

[dayshah]

Why are these changes needed?

Removes the unnecessary overhead of having the ClientCallTag and having call as a shared ptr. Also kills a string copy on every call used to record timings.

Related issue number

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• Testing Strategy
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This pull request has been automatically marked as stale because it has not had any activity for 14 days. It will be closed in another 14 days if no further activity occurs. Thank you for your contributions.

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[github-actions[bot]]

This pull request has been automatically marked as stale because it has not had any activity for 14 days. It will be closed in another 14 days if no further activity occurs. Thank you for your contributions.

You can always ask for help on our discussion forum or Ray's public slack channel.

If you'd like to keep this open, just leave any comment, and the stale label will be removed.

[github-actions[bot]]

This pull request has been automatically marked as stale because it has not had any activity for 14 days. It will be closed in another 14 days if no further activity occurs. Thank you for your contributions.

You can always ask for help on our discussion forum or Ray's public slack channel.

If you'd like to keep this open, just leave any comment, and the stale label will be removed.