Preparing release v1.73.0

[biosvs]

• Upgraded go version to 1.21, set toolchain version.
• Reverted rpc-caller-procedure value setting.
• Reverted header renaming for tchannel: caller-procedure header changed back from rpc-caller-procedure to $rpc$-caller-procedure.
• Upgraded grpc-go to v1.44.0
• Fixed grpc status mapper, IDLE connections are now considered as available.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 85.20%. Comparing base (4d4c3a6) to head (e4ef7a0). Report is 43 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #2280 +/- ## ========================================== + Coverage 84.18% 85.20% +1.02% ========================================== Files 216 270 +54 Lines 12937 15557 +2620 ========================================== + Hits 10891 13256 +2365 - Misses 1702 1877 +175 - Partials 344 424 +80 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.