feat: enable extra counters in HAProxy metrics collection

Add extra-counters parameter to HAProxy Prometheus endpoint to collect
additional performance metrics for enhanced monitoring capabilities

Author: elasticroentgen

roles/haproxy_lb/files/vector.yaml

@@ -3,4 +3,4 @@ sources:
   metrics_haproxy:
     type: prometheus_scrape
     endpoints:
-      - http://127.0.0.1:9142/metrics
+      - http://127.0.0.1:9142/metrics?extra-counters=on