Searchlight project is retiring in Wallaby cycle[1].
This commit removes the ansible roles of Searchlight project
before its code is removed.

Needed-By: https://review.opendev.org/c/openstack/searchlight/+/764526

[1] http://lists.openstack.org/pipermail/openstack-discuss/2020-November/018637.html

Change-Id: I85aab66376ea4f1376c2705066ba3c7e5645644f