Replace the `project/issues/issues.feature` spinach test with an rspec analog

What does this MR do?

1. This MR moves all the tests from the features/issues/issues.feature spinach spec to an rspec analog.
2. Some specs refactoring while moving spinach tests.
3. Some helpers refactoring while moving spinach tests.

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

No.

Why was this MR needed?

This is a part of the spinach removal campaign.

Screenshots (if relevant)

No.

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
  • Has been reviewed by Backend
  • Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• Internationalization required/considered
• End-to-end tests pass (package-and-qa manual pipeline job)

What are the relevant issue numbers?

#23036 (closed)