Resolve "Cross-reference icon no longer visible in normal sidebar"

What does this MR do?

• Fixes the scrolling behaviour of the sidebar so the reference section is visible again.
• Caches the jQuery Lookups during init as they were executed everytime on every scroll
• Debounce for the resize event

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

If the scrolling behaviour is correct

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• 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 #33942 (closed)