test: use in-cluster for all environments (single cluster testing)

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Co-Authored-By: Claude <[email protected]>

Author: justgithubaccount

platform/gitops/appsets/tenant-apps.yaml

@@ -75,11 +75,11 @@ spec:
                   team: product-team
           - list:
               elements:
-                - cluster: tst-cluster
+                - cluster: in-cluster
                   env: tst
-                - cluster: stg-cluster
+                - cluster: in-cluster
                   env: stg
-                - cluster: prd-cluster
+                - cluster: in-cluster
                   env: prd
   template:
     metadata: