Add missing "g" to commit id field in the server config file

Fixes #2043

The "commit_id" field is supposed to have the form:

  <version>-<seqno>g<sha1>

but was missing the "g".

Author: ndokos

server/ansible/roles/pbench-server-add-commit-id/tasks/main.yml

@@ -4,6 +4,6 @@
     path: "{{ pbench_server_install_dir }}/lib/config/pbench-server.cfg"
     section: pbench-server
     option: commit_id
-    value: "{{ pbench_version }}-{{ pbench_seqno }}{{ pbench_sha1 }}"
+    value: "{{ pbench_version }}-{{ pbench_seqno }}g{{ pbench_sha1 }}"
     backup: yes