Calculate top position with flash message after the request is received

What does this MR do?

Takes in consideration the flash alert message, which is already done in master. Moves the function to verify the top position after the ajax request has finished. - needs to be ported to master.

Screenshots (if relevant)

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 #34461 (closed)

/cc @ClemMakesApps @kushalpandya this needs to go in the next patch 😁