Add grenade-skip-level job

This adds a grenade job that specifically skips the last release,
to prove that we can do it. Such a job would facilitate a new
goal of a tick/tock release arrangement where slower-moving operators
could stick on the "tick" release and know that they can upgrade to
the next "tick" release directly.

See https://review.opendev.org/c/openstack/governance/+/828777
for a proposal on why this is needed, and
https://review.opendev.org/c/openstack/grenade/+/826101
for a similar skip level job that's being created from the
integrated grenade job

Change-Id: I8c1584176643a8086ffb23358176073a18c82b45
Signed-off-by: Goutham Pacha Ravi <gouthampravi@gmail.com>
Depends-On: If4820dd4ec7e05ade6eb4a82a328797102704570

zuul.d/grenade-jobs.yaml

@@ -90,3 +90,17 @@
         - manila-tempest-plugin
       tempest_test_regex: ^manila_tempest_tests.tests.api
       tox_envlist: all
+
+- job:
+    name: manila-grenade-skip-level
+    description: |
+      Grenade job that skips a release, validating that deployers can skip
+      specific releases as prescribed by our process.
+    parent: manila-grenade
+    vars:
+      # Move this forward when master changes to a new skip-level-allowed
+      # target release. Right now, this is wallaby because master is yoga.
+      # When master is A, this should become yoga, and so forth.
+      grenade_from_branch: stable/wallaby
+      grenade_localrc:
+        NOVA_ENABLE_UPGRADE_WORKAROUND: True

zuul.d/project.yaml

@@ -34,6 +34,8 @@
             voting: false
         - manila-grenade:
             voting: false
+        - manila-grenade-skip-level:
+            voting: false
         - manila-rally-no-ss:
             voting: false
         - manila-rally-ss: