Resolve reserved keyword conflict with variable names in path patterns

[aandreassa]

https://github.com/googleapis/google-cloud-ruby/pull/26358 introduced a path variable module, which conflicts with reserved keywords, failing generation.

Current plan is:

1. Introduce an owlbot rule to affected library and unblock generation (adding sufix _param).
2. Add a fix to the generator itself, where keyword names will be properly escaped.

Note: google-cloud-support-v2/.owlbot.rb already contains a similar patch and should be tested on upcoming change. In that example, the word case gets converted to ccase.

For reference, PiperOrigin-RevId: 650374217

Pointers: https://github.com/googleapis/gapic-generator-ruby/pull/1086