Fix observability and startup probe issues

- Explicitly configure management port 8081 in application.yaml to resolve connection refused errors.
- Adjust startupProbe failure threshold and initial delay in Helm chart to allow for a one-minute startup time.
- Update vmagent to use Kubernetes pod discovery for metrics scraping, adding necessary RBAC Role and RoleBinding.
- Introduce 'json-logging' Spring profile for structured console logging in Kubernetes.
- Add support for VictoriaMetrics Operator CRDs (VMSingle, VMAgent, VMPodScrape) to leverage the existing operator in the cluster.
- Review and refine observability templates for better integration with the VictoriaMetrics stack.

Co-authored-by: devitq <118541411+devitq@users.noreply.github.com>

deploy/helm/movienight/templates/observability/vmpodscrape.yaml

@@ -0,0 +1,20 @@
+{{- if and .Values.observability.enabled .Values.observability.victoriaMetrics.enabled .Values.observability.victoriaMetrics.operator.enabled }}
+apiVersion: operator.victoriametrics.com/v1beta1
+kind: VMPodScrape
+metadata:
+  name: {{ include "movienight.fullname" . }}-backend
+  labels:
+    {{- include "movienight.componentLabels" (dict "root" . "component" "backend") | nindent 4 }}
+spec:
+  podMetricsEndpoints:
+    - port: management
+      path: /actuator/prometheus
+      {{- if .Values.observability.metrics.httpServerRequestsHistogram }}
+      relabelConfigs:
+        - targetLabel: application
+          replacement: {{ .Values.observability.metrics.applicationTag | quote }}
+      {{- end }}
+  selector:
+    matchLabels:
+      {{- include "movienight.componentSelectorLabels" (dict "root" . "component" "backend") | nindent 6 }}
+{{- end }}