Enable restoring volumes with size smaller than default

[a-barinov]

No description provided.

[a-barinov]

This commit is harmless standalone as backend will not downsize volumes without additional commits.

[marmarek]

Thanks for the contribution!
You need to update tests - see CI log at https://gitlab.com/QubesOS/qubes-core-admin-client/-/jobs/2488973220

[a-barinov]

I miss he days when patches were submitted by email... Anyway, this PR needs to come in first, then I'll do a new PR for restore.py code change

[marmarek]

Anyway, this PR needs to come in first,

This isn't strictly true. import_with_size() allows importing volume even if given size is smaller than current volume size - there is no need to call resize separately. What you need to do, is to adjust _handle_volume_size to save the size somewhere, to be used as import_with_size() argument, instead of calling resize. Alternatively, refactor _handle_volume_size and _handle_volume_data into one function with two parameters, and adjust all places where it is called.