Move VBMCD service name into vars file

ansible/roles/virtualbmc-daemon/tasks/main.yml

@@ -1,8 +1,4 @@
 ---
-- name: Set service name
-  set_fact:
-    service: vbmcd
-
 - name: Ensure Python requirements are installed
   pip:
     requirements: "{{ '/'.join([role_path, 'files', 'requirements.txt']) }}"

ansible/roles/virtualbmc-daemon/vars/main.yml

@@ -0,0 +1,3 @@
+---
+# The name of the Virtual BMC daemon systemd service.
+service: vbmcd