Fix system note comparison and standardize note setup

What does this MR do?

• Fix system note comparison. We were comparing against double the message because there were two .original-note-content and jQuery combines the two nodes, https://jsfiddle.net/574qfbvx/
• Standardize note setup to dry things up and make sure if a system note ever does need to update, we collapse it properly.

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

Why was this MR needed?

• MR commit system notes were oddly displayed after polling update

Does this MR meet the acceptance criteria?

• Tests
  • Added for this feature/bug
  • 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 #32551 (closed)