Apply common prefix/suffix stripping to zeta2 and mercury (#47530)

Fixes an issue where edits would be shown like this:

<img width="1262" height="1072" alt="image"
src="https://github.com/user-attachments/assets/f3ec865a-4bf2-423c-8465-62a54a21a882"
/>

When they should be like this:

<img width="1260" height="388" alt="image"
src="https://github.com/user-attachments/assets/ac555a25-f222-48aa-b922-0ae5b9f4e260"
/>


Release Notes:

- N/A *or* Added/Fixed/Improved ...
bf19f03f51Max Brunsfeld committed on 1/25/2026, 2:07:59 AM· committed by GitHubparent4e64180
3 files changedLine totals unavailable