Reusable blocks: width settings not retained when full-width block made reusable.

[rickybanister]

Describe the bug
I added columns to my document, put some things inside them, decided I wanted my layout to be full width and changed that setting on the parent columns block. I then converted it to 'reusable' for use elsewhere. In the process my width setting was lost and my reusable block became the standard document width.

To reproduce
Steps to reproduce the behavior:

1. Create a new page.
2. Add a columns block and put content inside it.
3. Set the columns parent alignment to 'full width'.
4. Convert it to 'reusable'.
5. See the width jump back to default.

Expected behavior
I expected the 'reusable block' to just be a dumb wrapper and retain all my inner settings. I could get those back by 'converting to regular blocks', but then I'd lose the advantage of having cascading changes to the inner blocks. Perhaps another solution would be to provide alignment options for the reusable block wrapper, but I'm not sure that would solve the issue.

Screenshots
Columns block set to 'full width':

After converting to reusable:

[talldan]

I think this issue is covered by #17640, adding an alignment option to the reusable block toolbar would solve the problem, so I'll close this in favour of that issue.