The current rule fails to load with oslo.policy, the correct
value used to determine the admin project for the cloud_admin should
simply be: `is_admin_project:True`, since that is what is stored
in oslo.context.
This problem was masking a more serious issue that domain admin tokens
could be misinterpreted as cloud admin tokens.
Change-Id: I3ea562c01e06e6c519fdaec3ab6e1dac204ced71
Closes-Bug: 1547684
Closes-Bug: 1651989