fix(connections): Use baseline pod security to allow container initialization

- Set namespace pod-security.kubernetes.io/enforce to baseline
- Remove restrictive container securityContext
- Allows signal-cli-rest-api container to run its entrypoint script
  which requires user/group modification capabilities

cluster/platform/connections/namespace.yaml

@@ -6,3 +6,6 @@ metadata:
     app.kubernetes.io/name: connections
     app.kubernetes.io/component: messaging-gateway
     theme: epcot
+    pod-security.kubernetes.io/enforce: baseline
+    pod-security.kubernetes.io/audit: baseline
+    pod-security.kubernetes.io/warn: baseline