Catch dangling references at PR time: every recording-rule name used
inside a tracked GPU dashboard must exist in
packages/system/monitoring-agents/alerts/gpu-recording.rules.yaml. The
first iteration of gpu-efficiency.json shipped panels keyed on
pod:tensor_saturation:avg5m without the rule defined; the test fails
on exactly that class of bug.
Scoped to dashboards listed under gpu/* in dashboards-infra.list, so
untracked drafts stay out of scope until they are registered. Reverse
direction (rule defined but unused) is intentionally NOT enforced —
some rules exist for ad-hoc PromQL or upcoming dashboards.
Auto-discovered by make bats-unit-tests via hack/cozytest.sh.
Signed-off-by: Arsolitt <arsolitt@gmail.com>