chore(argocd): disable auto-sync for both Spark apps

Cluster saturated at 100% CPU due to Spark executor crash loop.
Disabling automated sync on spark-analytics and spark-cluster to prevent
further changes until cluster is stable.

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

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

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

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

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