Drop common-db tag from db_sync task

rally_db_setup has no relation to common-db, and independent step
during glance configuration. common-db tag should be applied only
to the common tasks

Change-Id: I1519de17454a4f7c89dbf93dd1827352746a884a

tasks/main.yml

@@ -66,5 +66,4 @@
 - include_tasks: rally_db_setup.yml
   when: inventory_hostname == groups[rally_role_project_group][0]
   tags:
-    - common-db
     - rally-config