De-vendor debefivm-create
debvm 0.4 is in trixie, with a newer version of debefivm-create. We should:
- update to this version (there are API changes)
 - un-vendor it (once 
debvmis backported to bookworm, or we drop support for bookworm workers) 
debvm 0.4 is in trixie, with a newer version of debefivm-create. We should:
debvm is backported to bookworm, or we drop support for bookworm workers)