Fix search bar filter dropdown scrollbars

What does this MR do?

Fixes the scrollbars so that they aren't visible unless they are needed (Mainly for windows)

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

None

Why was this MR needed?

Improves UI for windows users

Screenshots (if relevant)

Before:

After:

Does this MR meet the acceptance criteria?

• Tests
  • 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?

Closes #26777 (closed)