[services] Tunnelbroker - Removing rudimental ping message from the protobuf
Summary:
This diff removes the rudimental ping message from the protobuf.
The "pinging" message mechanism was changed to the gRPC keep-alive mechanism and the server implementation was changed in D5713. The empty "ping" message should be removed from the protobuf API as it's not used anymore.
Linear task: ENG-2405
Test Plan:
- Services are successfully built.
- CI tests passed.
Reviewers: jon, tomek, ashoat
Reviewed By: tomek, ashoat
Subscribers: ashoat, tomek, atul
Differential Revision: https://phab.comm.dev/D5809