Retire tempest-horizon

As disscussed in Wallaby PTG [1], QA and Horizon team
decided to move the horizon dashboard test from tempest-horizon
to Tempest. Scenario tests in tempest-horizon have been merged
into the tempest repository.

[1] https://etherpad.opendev.org/p/qa-wallaby-ptg

Depends-On: https://review.opendev.org/c/openstack/project-config/+/772373
Depends-On: https://review.opendev.org/c/openstack/horizon/+/771737
Change-Id: I6cc32a57dde4270343ca1f564ddc75f107455d9f
20 files changed
tree: 03846338b9ca642f4096bc0bd01e9dd86b0adea1
  1. .gitreview
  2. README.rst