E2E test: ignore spinner in codeowners spec

What does this MR do and why?

Resolves #403189 (closed)

#403189 (closed) is failing due to this bug.

The ee/browser_ui/3_create/repository/assign_code_owners_spec.rb E2E test is frequently failing due to this bug since there is a never ending spinner on the page. This MR simply doesn't wait for requests before clicking the Edit MR button.

Even though it isn't really necessary for this test to wait for the MR page to finish loading (it will simply just wait for the edit button to appear and click it), I have added a TODO to remove this once #398559 (closed) is fixed.

How to set up and validate locally

QA_LOG_LEVEL=DEBUG QA_GITLAB_URL=http://192.168.4.31:3000  bundle exec rspec qa/specs/features/ee/browser_ui/3_create/repository/assign_code_owners_spec.rb

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