Tiled Galleries: Gallery blocks are not transformed to Tiled Gallery block when selecting media setting to make tiled the default

### Impacted plugin

Jetpack

### Steps to Reproduce

1. Create a post w/a core WordPress gallery
2. Navigate to "Settings > Media" and check the box next to "Display all your gallery pictures in a cool mosaic"
3. View the post. It still displays as a standard gallery

### A clear and concise description of what you expected to happen.

I expected this would display as a Jetpack Tiled Gallery

### What actually happened

Does not display as Jetpack Tiled Gallery

### Browser

Google Chrome/Chromium, Mozilla Firefox

### Other information

Raised on forums:

https://wordpress.org/support/topic/tiled-gallery-settings-are-not-working/?view=all

I tested with Twenty Twenty and Twenty Twenty One themes

### Platform (Simple, Atomic, or both?)

Self-hosted

### Reproducibility

Consistent

### Severity

Some (< 50%)

### Available workarounds?

None

### Workaround details

_No response_

The issue names no files or tests. Reproduce the behavior with a core WordPress gallery and the Settings > Media tiled-gallery option, then trace Jetpack's gallery transformation and rendering entry points. Done means the same post displays as a Jetpack Tiled Gallery when that setting is enabled, including with the Twenty Twenty and Twenty Twenty One themes.

Written by the indexing model from the issue text.