EDGEPOD-60 Add support of multiple UPFs

- Enable configuring multiple UPF mode
- Add support of ZMQ mode when multple UPF enabled
- Change to create three types of services for each application,
  cluster IP, headless, and external

Change-Id: Ic004a4ff7cdc5708d28ce2717677041f71b4d819
diff --git a/omec/omec-data-plane/templates/statefulset-spgwu.yaml b/omec/omec-data-plane/templates/statefulset-spgwu.yaml
index 11749e7..07f9082 100644
--- a/omec/omec-data-plane/templates/statefulset-spgwu.yaml
+++ b/omec/omec-data-plane/templates/statefulset-spgwu.yaml
@@ -19,6 +19,7 @@
 kind: StatefulSet
 metadata:
   name: spgwu
+  serviceName: spgwu-headless
   labels:
 {{ tuple "spgwu" . | include "omec-data-plane.metadata_labels" | indent 4 }}
 spec: