Update v3 identity project tag test to work w/ pre-prov

I don't see any limitations by using pre-provisioned
credentials for these test:

* test_list_update_delete_project_tags

By setting force_tenant_isolation=False these tests now be
can executed with backends that don't allow user creation
(immutable user source) like LDAP.

Change-Id: I04a0a00b8a33686038754f32c2f722e0e522fc4d
1 file changed