Resolve "QA: Deploy key cloning test sometimes can't find the QA element"

What does this MR do?

This ensures we wait for the deploy key list to be visible before trying to interact with it.

Why was this MR needed?

Because default Capybara timeout is 10 seconds and on staging it can take more than 10 seconds for the deploy key list to appear.

Does this MR meet the acceptance criteria?

• Conform by the code review guidelines
  • Has been reviewed by a Backend maintainer
• 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 #48243 (closed)