Changing layout selection of existing content does not work as expected

Here's a patch for this. I went with disabling the Layout field on the entity edit form, but we could also choose to hide it completely, I've no strong preference either way.

Fixed the failures. This patch conflicts with ✨ Support Layout Builder Restrictions RTBC , which is RTBC, so posting a patch that applies on top of that one.

Tested, works great!

Thanks for reviewing! Here's a better check for when to disable the layout selection field.

This should work better :)

I've applied the patch. But I didn't see `Change layout template` button anywhere. Can you please guide us where can we find it?

Further testing of this patch revealed that it wasn't possible to select a layout template for an entity that was initially created without a template, so here's a fix for that.

@pradeepjha, maybe that's the problem you bumped into as well. In any case, for a entity that has a template selected, the Change layout template button can be found on the Layout tab, see the screenshot below:

Note that this patch still has to be applied on top of the MR from ✨ Support Layout Builder Restrictions RTBC .

Simplifying the title. Ran into this problem today and it was definitely a head-scratch.

This technically works, but it introduces a new workflow and new terminology ("layout template") which might be confusing.

Would it be possible instead to change the selector on the entity to just indicate whether the current layout has been overridden, and then give a warning if it is changed that the current overrides will be lost?