Display click to expand on collapsed diffs

What does this MR do?

Fixes absent block of "Click to expand" on collapsed diffs, not rendered at initial load.

After 5k lines are displayed on the initial load of the Changes tab, the rest of the files will start collapsed.

This, however, was not causing the Click to expand to show properly.

before
after

What are the relevant issue numbers?

Closes #51466 (closed)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• Tests added for this feature/bug
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides