Make maru versions OCI-observable and fix metrics scrape path.

Re-label consensys/maru FROM tag into image OCI labels (upstream leaves
version/vcs-ref empty) and scrape /metrics on :9090 instead of the 404ing
/debug/metrics/prometheus path.

Co-authored-by: Cursor <cursoragent@cursor.com>

linea/besu/linea-sepolia-besu-pruned-bonsai.yml

@@ -150,7 +150,7 @@ services:
     labels:
       - prometheus-scrape.enabled=true
       - prometheus-scrape.port=9090
-      - prometheus-scrape.path=/debug/metrics/prometheus
+      - prometheus-scrape.path=/metrics
 
 volumes:
   linea-sepolia-besu-pruned-bonsai: