The code should be rewritten anyway (see
https://storyboard.openstack.org/#!/story/2002787)
and in general the detection of the dashboard location
should be more roboust, but the code should not raise
an exception.
and horizon settings are relevant only for the (few)
Horizon Tempest tests, but the system can otherwise work.
Change-Id: I62607ce4de65062a0c37bdd23220edf9ea7e6818
Story: 2003024
Task: 23048
2273794919