Revert "Move github push_rule import validation to ee, improve spec namings"

What does this MR do and why?

Closes #380973 (closed)

The changes Move github push_rule import validation to ee, ... (!102477 - merged) appears to have introduced a conflict causing some failures to api/1_manage/rate_limits_spec.rb seen in #380921 (closed).

This is actually impacting a far bigger number of tests - many of the failing issues from gitlab-org/quality/testcase-sessions#58522 (closed) even seem to exhibit similar errors in the stack trace on the pipeline jobs.

The issue seems to be caused as some of the methods in github_import_shared_context are getting called unexpectedly.

How to set up and validate locally

bundle exec rspec ./qa/specs/features/api/1_manage/rate_limits_spec.rb

MR acceptance checklist

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