WIP: Kubernetes autoscaling

Enable Kubernetes autoscaling:

• metric provisioning (metrics-server, prometheus adapter)
• autoscaling based on kubernetes hpa2
• add more config parameters to the execution scripts

execution/infrastructure/horizontal-pod-autoscaler/custom-hpa.yaml

+apiVersion: autoscaling/v2beta2
+kind: HorizontalPodAutoscaler
+metadata:
+  name: titan-ccp-aggregation
+  namespace: default
+spec:
+  scaleTargetRef:
+    apiVersion: apps/v1
+    kind: Deployment
+    name: titan-ccp-aggregation
+  minReplicas: 1
+  maxReplicas: 6
+  metrics:
+    - type: Object
+      object:
+        metric:
+          name: kafka_consumergroup_group_lag
+          selector: {matchLabels: {topic: input}}
+        describedObject:
+          #apiVersion: networking.k8s.io/v1beta1
+          kind: Service
+          name: kafka-lag-exporter-service
+        target:
+          type: Value
+          value: 1k
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