Add nova-ceph-multistore job in devstack gate

nova-ceph-multistore is defined in nova side to test the
glance multistore on ceph and it is voting on nova gate.

There are other multistore testing enhancement going on for
example- https://review.opendev.org/#/c/743800/. so to avoid
any regression, let's run exiting mutistore job on devstack
gate too.

Change-Id: Ie82b4057463df4b6138c53b14a582bd84866aebd
diff --git a/.zuul.yaml b/.zuul.yaml
index d387b0d..9ae5f3f 100644
--- a/.zuul.yaml
+++ b/.zuul.yaml
@@ -734,6 +734,10 @@
             irrelevant-files:
               - ^.*\.rst$
               - ^doc/.*$
+        - nova-ceph-multistore:
+            irrelevant-files:
+              - ^.*\.rst$
+              - ^doc/.*$
         # NOTE(gmann): Remove this job from devstack pipeline once it is
         # migrated to zuulv3 native. This is legacy job and rely on
         # devstack-gate + devstack setting so any change in devstack can
@@ -770,6 +774,10 @@
             irrelevant-files:
               - ^.*\.rst$
               - ^doc/.*$
+        - nova-ceph-multistore:
+            irrelevant-files:
+              - ^.*\.rst$
+              - ^doc/.*$
     # Please add a note on each job and conditions for the job not
     # being experimental any more, so we can keep this list somewhat
     # pruned.