use the variable holding the service types url instead of an inline value
use the variable holding the service types url instead of an inline value

There is a global variable with the URL for the service types authority
list. Use that instead of the hard-coded value.

Change-Id: I05187afd72b3e18c6308dba257fcc4d41e604d7e
Signed-off-by: Doug Hellmann <0798ebecfb7bc4dfb9d0445c2fa030eb64e1fa1c@doughellmann.com>

openstack/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals