Fix backup metadata import missing fields

Fix backup metadata import missing fields

When importing backup metadata only required fields were being imported,
and all other fields were being ignored.

This led to some serious problems when importing backups back, since
you would lose not only the original Volume ID, but also relevant parent
id information needed to restore incremental backups.

This patch fixes this by importing everything back and creating backup
records with the right ID.

Closes-Bug: #1455043
Closes-Bug: #1476416
Depends-On: Id7ab6e174c1fe85772477f03059c4f457c5c8b17
Change-Id: Ia42ba73e9078d993c63f8e16308151ad11721ea9