Gitaly: remove ruby related configuration
Now that gitaly!5497 (merged) has been merged, Gitaly no longer runs the Ruby sidecar and hence no longer needs any Ruby related configuration. We can remove all ruby related configuration values.
NOTE: per discussion with @twk3, and the omnibus deprecation policy, we need to first mark these configurations as deprecated and then we can fully remove them in 17.0. The Gitaly pass through will still let these values through to the config.toml, but Gitaly will simply ignore them.
Edited by John Cai