conf: Always format storage source auth and encryption under <source> for backing...

conf: Always format storage source auth and encryption under <source> for backing files

Historically there are two places where we format authentication and
encryption for a disk. The logich which formats it for backing files was
flawed though and didn't format it at all. This worked if the image
became a backing file through the means of a snapshot but not directly.

Force formatting of the source and encryption for any non-disk case to
fix the issue.

This caused problems in many places as we use the formatter to copy the
definition. Effectively any copy lost the secret definition.

https://bugzilla.redhat.com/show_bug.cgi?id=1789310
https://bugzilla.redhat.com/show_bug.cgi?id=1788898

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Jiri Denemark <jdenemar@redhat.com>