Remove prometheus global rule causing plugin not found error

Removed the prometheus-metrics global rule configuration which was
causing "custom plugin (prometheus-metrics) not found" error.

API7 Enterprise doesn't support prometheus as a global rule plugin
in this configuration format. Prometheus metrics can be configured
differently if needed.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

helm/api7ee-demo-k8s/templates/configmap-adc.yaml

@@ -129,12 +129,6 @@ data:
 
     # Global Rules
     global_rules:
-      {{- if .Values.api7.plugins.prometheus.enabled }}
-      prometheus-metrics:
-        plugins:
-          prometheus:
-            prefer_name: true
-      {{- end }}
       {{- if .Values.api7.plugins.logging.enabled }}
       request-logging:
         plugins: