Small UI tweaks on search results pages

What does this MR do and why?

• Remove unnecessary spaces and horizontal lines
• Clean up margins/padding
• Combine help links (check what else we could do here)
• Remove space between project/group labels and dropdown

Todo:

• Remove button to open filters (is this needed? we already have the fixed button to open the sidebar from the breadcrumb bar at the top) (separate MR)
• Code results fixes (separate MR)
• Add page header? (separate MR)
• Check layout when elasticsearch is disabled

What does this MR not do?

Changes to empty states

Screenshots or screen recordings

Elasticsearch enabled

Before	After

Elasticsearch disabled

Before	After

How to set up and validate locally

• Enable elasticsearch
• Go to search page (ie http://127.0.0.1:3000/search)

Links

• ✂️ UX Paper Cuts 17.0 → Search and Filter (#444717 - closed)