fix(instance) ensure root size copy for containers is clear

[edlerd]

Done

• fix(instance) ensure root size copy for containers is clear
• drive-by: fix imports

Fixes WD-34782

QA

1. Run the LXD-UI:
   • On the demo server via the link posted by @webteam-app below. This is only available for PRs created by collaborators of the repo. Ask @Kxiru or @edlerd for access.
   • With a local copy of this branch, build and run as described in the docs.
2. Perform the following QA steps:
   • check instance > configuration > disk for a container and vm. for vms should specify 10GB and for containers "not specified" as default size of the root disk

Screenshots

[webteam-app]

Demo

Jenkins

demos.haus