Resolve "Pipelines view should handle empty state and buttons properly"

What does this MR do?

Handles empty states better in pipelines page:

User has permissions on current project to initiate CI
User has CI set up and a list of pipelines
Something went wrong
User has CI set up and clicked a tab with no pipelines (for example the "pending" tab)
User has no CI set up (either internal or mirrored/imported gitlab_ci)
Mirrored/imported gitlab_ci CI or imported a project with CI set up and no pipelines

User does not have permissions on current project to initiate CI	--
CI set up and a list of pipelines
Something went wrong
CI set up and clicked a tab with no pipelines (for example the "pending" tab)
No CI set up (either internal or mirrored/imported gitlab_ci)
Mirrored/imported gitlab_ci CI or imported a project with CI set up and no pipelines

Fixes loading icon margin in MR & Commits pages:

Merge Request/Commit

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-qa manual pipeline job)

What are the relevant issue numbers?

Closes #38587 (closed)