Upgrade gRPC to v1.62.1
Upgrade gRPC from v1.60.1 to v1.62.1.
gRPC v1.60.1 contains a regression which causes graceful stop
to no longer wait for all handlers to exit prior returning from
the server.GracefulStop() call. This causes flakes in our tests
that rely on logging. Our logging handler runs after an RPC has
finished causing GracefulStop() to return before the log messages
have been emitted and all handler goroutines have exited. This
regression has been fixed in gRPC v1.61.0 and later. Upgrade the
dependency version to fix the test flakes.
We've also recently moved all of our logging to happen in the stats handler, not the interceptors. Stats handler runs after the RPC finishes and thus is affected by this regression.