chore(argocd): re-enable auto-sync for Spark apps

Cluster stable. Re-enabling automated sync on spark-analytics and
spark-cluster. Driver DNS fix and Recreate strategy already in main,
so next sync deploys the corrected manifests.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

eu-central-1/argo-apps/spark-analytics/spark-analytics.yaml

@@ -12,4 +12,7 @@ spec:
     - repoURL: git@git.janis-eccarius.de:NowChess/Gitops.git
       path: ./spark-analytics/eu-central-1-prod
       targetRevision: main
-  syncPolicy: {}
+  syncPolicy:
+    automated:
+      prune: true
+      selfHeal: true

eu-central-1/argo-apps/spark-cluster/spark-cluster.yaml

@@ -12,4 +12,7 @@ spec:
     - repoURL: git@git.janis-eccarius.de:NowChess/Gitops.git
       path: ./spark-cluster/eu-central-1-prod
       targetRevision: main
-  syncPolicy: {}
+  syncPolicy:
+    automated:
+      prune: true
+      selfHeal: true