Rails 5 fix Capybara::ElementNotFound: Unable to find visible css #modal-revert-commit

What does this MR do?

Add an extra wait_for_requests in two failing Rails5 feature specs. Not sure why this is needed for Rails 5 though.. I see some overlapping requests in the logs that are consecutive in Rails 4.

Are there points in the code the reviewer needs to double check?

Why was this MR needed?

rails5 upgrade

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Conform by the code review guidelines
  • Has been reviewed by a UX Designer
  • Has been reviewed by a Frontend maintainer
  • Has been reviewed by a Backend maintainer
  • Has been reviewed by a Database specialist
• Conform by the merge request performance guides
• Conform by the style guides
• If you have multiple commits, please combine them into a few logically organized commits by squashing them
• Internationalization required/considered
• End-to-end tests pass (package-and-qa manual pipeline job)

What are the relevant issue numbers?

Closes #48140 (closed) and #48139 (closed)