chore: Remove Ruby bits (#1725)

# What does this PR do?

Remove Ruby bits

# Motivation

These have been migrated to: https://github.com/DataDog/libdatadog-rb

# Additional Notes

As an alternative it was suggested to leave a README explaining the migration, but I don't think any interested party would be surprised since they are all aware of the change.

# How to test the change?

Non-ruby things do not break?

Co-authored-by: edmund.kump <edmund.kump@datadoghq.com>

Author: lloeki

.github/CODEOWNERS

@@ -60,7 +60,6 @@ local-linux.Dockerfile               @DataDog/libdatadog
 NOTICE                               @DataDog/libdatadog
 README.md                            @DataDog/libdatadog
 repository.datadog.yml               @DataDog/apm-common-components-core
-ruby/                                @DataDog/ruby-guild
 rustfmt.toml                         @DataDog/libdatadog-core
 scripts/check_cargo_metadata.sh      @DataDog/libdatadog-core
 scripts/commits-since-release.sh     @DataDog/libdatadog-core