Export cluster RAM metrics for MintMaker (#7304)

This commit exports two metrics that will be important for monitoring
MintMaker service quality.

The metrics are already contributed to 'o11y', now we need to export
them in order to have them available in the monitoring stack.

Author: FernandesMF

components/monitoring/prometheus/base/monitoringstack/monitoringstack.yaml

@@ -167,6 +167,8 @@ spec:
         - '{__name__="kube_deployment_status_replicas_ready", namespace="mintmaker"}'
         - '{__name__="kube_deployment_status_replicas_available", namespace="mintmaker"}'
         - '{__name__="kube_deployment_spec_replicas", namespace="mintmaker"}'
+        - '{__name__="cluster_ram_requested_perc"}'
+        - '{__name__="node_memory_pressured_perc"}'
 
         # Namespace (expression):  ~".*monitoring.*"
         - '{__name__="kube_deployment_status_replicas_ready", namespace=~".*monitoring.*"}'