Upgrade to grpc v1.63.0

This release fixes two key issues with the Ruby gem:

* https://github.com/grpc/grpc/pull/33565
* https://github.com/grpc/grpc/pull/36125

We added a monkey patch for the first pull request, but now that the
fix has been merged upstream we can drop it. This has the added
benefit of eliminating an occasional test seg fault due to a race
condition in the gRPC shutdown code.

The second pull request doesn't affect us since we aren't using Ruby
3.3 yet.

Relates to https://gitlab.com/gitlab-org/gitlab/-/issues/426677

Changelog: fixed