watcher-grenade-skip-level-always job will tests upgrade from
N-2 to N release.
Note:
- It also adds scenario tests in grenade job
- It also drops unused from_rocky upgrade devstack file.
- It adds the new job to check and gate pipeline.
Change-Id: Iaf1a2ae5c4dfb3df39902d1b66a98152068a9349
Signed-off-by: Chandan Kumar (raukadah) <chkumar@redhat.com>