WIP: prevent MR tabs from jumping when switching between them

Open Simon Knox requested to merge 33237-mr-tab-jump into master

TODO:

  • use $('body').css({ minHeight: `${document.body.scrollHeight}px` }); instead
  • remove minHeight after load

What does this MR do?

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

Why was this MR needed?

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

What are the relevant issue numbers?

Closes #33237 (moved)