Fix test_identity_list_limits for Domain Admin

The patch that fixes bug#2137711 [1] changed the default policy for
`GET /v3/limits`.  The new policy allows users with the "admin" role on
any scope to get an unfiltered list of limits.

With this policy change, Domain Admins can now see all limits querying
the limits API.  This patch updates the test for this persona for this
API to reflect the policy change.

[1] https://opendev.org/openstack/keystone/commit/8a42793e714efb0b5c1bb07bcb81d2b4ab59b600

Related-Bug: #2137711
Signed-off-by: Douglas Mendizábal <dmendiza@redhat.com>
Change-Id: I81d11b2dbb54b4256886fe5daf6a68650c26d87f
1 file changed