fix: remove non-existing label

_data/rules.yml

@@ -1943,7 +1943,7 @@ groups:
                 query: (sum by (proxy) (rate(haproxy_server_connection_errors_total[1m]))) > 100
                 severity: critical
               - name: HAProxy backend max active session > 80%
-                description: Session limit from backend {{ $labels.proxy }} to server {{ $labels.server }} reached 80% of limit - {{ $value | printf "%.2f"}}%
+                description: Session limit from backend {{ $labels.proxy }} reached 80% of limit - {{ $value | printf "%.2f"}}%
                 query: ((haproxy_backend_current_sessions >0) * 100) / (haproxy_backend_limit_sessions > 0) > 80
                 severity: warning
                 for: 2m