Revert "Merge branch 'ps-ruby-grpc-update' into 'master'"
This reverts merge request !2319 (merged). We had two issues:
- We can't update google-protobuf until we drop support for CentOS 6 (see !2088 (merged)).
- The gRPC gem was tied to macOS and doesn't work with Linux.
Edited by GitLab Release Tools Bot