Update roles required for testing

This patch removes the hard-coded 'key-manager:service-admin' role from
the base test class because the role is not available in deployments
with the new Secure RBAC policies enabled.

There is only one test that still requires this role in the API quotas
tests, so we generate a dynamic user there and only use it in this
class.  This test is skipped when SRBAC is enabled.

Change-Id: I6fbfe43f821d9315e01d3bdfd6f5d4edf4e552b7
3 files changed