Zuul is changing how queues are declared[1]. This patch drop
the explicit queue definition for Designate client since it is inherited
via the designate-devstack-jobs template.
This change also drops the `lower-constraints` job and amends the doc
requirements to match global requirements.
[1] https://lists.zuul-ci.org/pipermail/zuul-discuss/2022-May/001801.html
Change-Id: Ibf3bab374ec3a5bec842051c29d18864d42c02b8
(cherry picked from commit ef2098e654)