Enhancement: AI Assistant Paragraph Block - Update "Try Again" Copy

### Impacted plugin

Jetpack

### What

Consider renaming the "Try Again" copy to something that makes it clearer it will undo the generated content.

### How

When you use the AI Assistant to update the text in a paragraph block, there's no clear way to "undo" the generated prompt and go back to the original. This is the job of the "Try Again" button, but I missed that when testing because I assumed it was going to just re-generate a new AI response. Maybe something like "Cancel" or "Original Text"?

Surfaced during internal testing: p8oabR-1jo-p2#comment-7510

No file or test is named in the issue. Start by locating the AI Assistant paragraph block and its “Try Again” label, then verify how the action restores the original text. Done means the button copy clearly communicates that it returns to the original content.

Written by the indexing model from the issue text.