Audit Jetpack blocks for contentOnly

Similar to the work being done in [Core to audit blocks for the new Write mode](https://github.com/WordPress/gutenberg/issues/65778) and contentOnly capability, I wanted to kick off an issue to do the same for Jetpack blocks as they are greatly embedded on WordPress.com and in the wider WordPress ecosystem and it would be ideal for these blocks to be prepared for this feature sooner rather than later. As a reminder, contentOnly within Patterns seeks to offer a simplified editing experience where the focus is on content related changes with only section level styling options available.

For more information:

- https://developer.wordpress.org/news/2024/11/05/how-to-add-content-only-editing-support-to-a-block/
- https://github.com/WordPress/gutenberg/issues/71517

Please add and edit this issue as you find more Jetpack blocks that need to be updated.

## Blocks

### Contact Form

- #40955

### Subscribe

- [ ] User cannot edit the placeholder text

### Contact info

- [ ] User cannot edit any field text, whether edited or not

### Paid content

- [ ] User cannot edit any buttons

### Map

- [ ] https://github.com/Automattic/jetpack/issues/40712

Review the listed Contact Form, Subscribe, Contact info, Paid content, and Map blocks, then read the linked Core contentOnly audit and the provided contentOnly guidance. Inspect each block's current editing behavior and the related Map issue #40712. Done means the listed blocks support the intended content-only editing experience, with the checklist updated as each block is addressed.

Written by the indexing model from the issue text.