Slideshow Block captions are not preserved when transforming to Tiled Gallery and back

### Impacted plugin

Jetpack

### Quick summary

When you add a slideshow block the captions display properly on every image but if you change the layout and then go back to slidehow the captions are gone.

### Steps to reproduce

When you add a slideshow block the captions display properly on every image, when you switch to a layout that doesn't support captions like tiled gallery and then switch back to slideshow captions are gone.

1 - Add a slideshow block and make sure the images have captions, it will display properly:


2 - Switch the layout to one that doesn't support captions, like tiled gallery.


3 - Change the layout back to slideshow, notice that the captions are gone


### Site owner impact

More than 60% of the total website/platform users

### Severity

Minor

### What other impact(s) does this issue have?

_No response_

### If a workaround is available, please outline it here.

if you click on edit for the slideshow then click update without changing anything the captions will show again

### Platform (Simple and/or Atomic)

_No response_

Reproduce the issue by creating a Slideshow Block with image captions, switching to Tiled Gallery, and switching back. Trace the slideshow and gallery layout transformation entry points, then verify that captions remain visible after returning to slideshow; the issue names no specific files or tests.

Written by the indexing model from the issue text.