Refactor scope to support type: all in GitClassProxy & rubocop cleanup

What does this MR do and why?

Related to #411310 (closed)

This MR has multiple commits which do the following:

1. refactor setting scope in the options field for Elastic::Latest::GitClassProxy
2. fix all of the rubocop todos that were easy to fix/located in .yml files. There are still a few manual rubocop disables in the file but those felt harder to fix.
3. change ee/spec/lib/elastic/latest/git_class_proxy_spec.rb to :elastic trait vs. :elastic_clean and switch to let_it_be, this significantly speeds up the testing run time: Reduced from 13 minutes 15 seconds to 1 minute 56.34 seconds!

Screenshots or screen recordings

N/A

How to set up and validate locally

No real change to behavior, just code refactoring. I'm relying upon the specs

MR acceptance checklist

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