Test Helm chart in CI pipeline

Open points:

• Basic k3d cluster setup
• Move all installation etc. to dedicated builder image

Postponed to later MR:

• Use custom builder image (!283 (merged))
• Create test for running a simple benchmark (unsure if this should be done via helm test as the test pod/job would need a service account etc.), related to #202 (closed) (!285 (merged))
• Add need for deploy-theodolite (#389)

helm/templates/tests/test-prometheus-connection.yaml

+{{- if .Values.prometheus.enabled }}
 apiVersion: v1
 kind: Pod
 metadata:
@@ -5,7 +6,8 @@ metadata:
   labels:
     {{- include "theodolite.labels" . | nindent 4 }}
   annotations:
-    "helm.sh/hook": test-success
+    "helm.sh/hook": test
+    "helm.sh/hook-delete-policy": hook-succeeded
 spec:
   containers:
     - name: wget
@@ -13,3 +15,4 @@ spec:
       command: ['wget']
       args: ['http://prometheus-operated:9090']
   restartPolicy: Never
+{{- end }}