This commit includes multiple fixes to
make gate happy:
1. Use packaged uwsgi on Fedora and Ubuntu
- https://review.opendev.org/#/c/735615/7
2. Move process-stackviz role from Tempest to Devstack
- https://review.opendev.org/#/c/737078/4
3. Add ensure-pip to pre.yaml
- https://review.opendev.org/#/c/738495/2
4. Temporarily disable the grenade jobs
Change-Id: I82f539bfa533349293dd5a8ce309c9cc0ffb0393
(cherry picked from commit 2d903568ed)