Increase NetworkPolicy propagation wait time for boutique test

12 services with complex policies need more time to propagate across
all nodes than the basic 3-service lab.

Author: fenio

.github/workflows/integration.yml

@@ -198,7 +198,7 @@ jobs:
         run: echo "y" | ./harden.sh
 
       - name: Wait for NetworkPolicy propagation
-        run: sleep 5
+        run: sleep 15
 
       - name: Test connectivity (after hardening)
         working-directory: examples/kind-lab-boutique