Fix warnings for duplicated policy rules
There are so many warning messages appear while running tests. It's
because of a change in `oslo.policy` for notifying that some policy
rules are the same as default. So, this change removes duplicated
policies from policy file.
Closes-Bug:
-"context_is_admin": "role:admin"
"admin_or_owner": "rule:context_is_admin or tenant_id:%(tenant_id)s"
"admin_only": "rule:context_is_admin"
"regular_user": ""
"shared": "field:vims:shared=True"
-"default": "rule:admin_or_owner"
"get_vim": "rule:admin_or_owner or rule:shared"
