decomission unifolium/kvm2, 6 VMs to migrate

• cupani.torproject.org (git-rw) migrated in #33446 (moved)
• polyanthum.torproject.org (bridges) #33448 (moved)
• omeiense.torproject.org (onionoo.torproject.org) (possibly to decom? see #32268 (moved)) #33447 (moved)
• savii.torproject.org (static content backend) retired in #33441 (moved)
• build-x86-07.torproject.org (buildbox) retired in #33442 (moved))
• bracteata.torproject.org (sandstorm) retired in #32390 (moved)

Requires a new gnt node (#33081 (moved)).