Replace 'starred_projects.feature' spinach test with an rspec analog

What does this MR do?

This MR replaces current spinach feature test features/dashboard/starred_projects.feature with an rspec analog.

Why was this MR needed?

This is a part of spinach tests removal campaign.

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Part of #23036 (closed)