Convert hack/e2e-apps/backup.bats.disabled to a Chainsaw test under
hack/e2e-chainsaw/backup/. It stays opt-in: the chainsaw-test.yaml.disabled
filename keeps it out of chainsaw's default discovery and out of
hack/select-e2e.sh enumeration, matching the previous disabled state.
The declarative readiness chain (Bucket -> VirtualMachine -> BackupJob) becomes
assert operations; the imperative Velero-backup + S3 verification stays a single
script step, mirroring the bucket suite. README documents the opt-in run command
and the backup-infra preconditions.
Assisted-By: Claude <noreply@anthropic.com>
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Signed-off-by: Myasnikov Daniil <myasnikovdaniil2001@gmail.com>
