Remove some racing expectations

What does this MR do?

Fixes a racy spec causing ~"broken master" problems. As @smcgivern pointed out, if the ajax request completes quickly, then we'll never see the spinner appear and disappear.

I don't think we get much value out of checking for the spinner, so I'm happy to just remove these. Thoughts, @dbalexandre ?

What are the relevant issue numbers?

Closes https://gitlab.com/gitlab-org/gitlab-ee/issues/9648

Does this MR meet the acceptance criteria?

• [-] Changelog entry added, if necessary
• Tests added for this feature/bug
• Security reports checked/validated by reviewer