fix(kustomize): use create behavior for generators

Change configMapGenerator and secretGenerator behavior from 'merge'
to 'create' since target ConfigMap/Secret don't exist on first deploy.
'merge' only works when the resource already exists.

k8s/kustomization.yaml

@@ -17,8 +17,8 @@ secretGenerator:
   - name: poimen-secrets
     envs:
       - secrets.env
-    behavior: merge
+    behavior: create
 
 configMapGenerator:
   - name: poimen-config
-    behavior: merge
+    behavior: create