Add collapsable sections for Pipeline Settings

What does this MR do?

Adds collapsible sections for Pipeline Settings to greatly improve the usability of that page. It follows the same pattern as we have for settings.

Why was this MR needed?

The UX of the current page is terrible. We all agree here :)

Screenshots (if relevant)

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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

What are the relevant issue numbers?

Closes #37275.