Add nova-live-migration to experimental queue jobs

The legacy-tempest-dsvm-multinode-live-migration job is being moved
into the nova repo and renamed to nova-live-migration. This change adds
the new job name to the in-tree definition of the experimental queue
jobs that run on tempest changes. A project-config change will depend
on this patch to undefine the legacy job name from being used on
tempest changes.

Depends-On: https://review.openstack.org/555945

Change-Id: If8150527a358cfe634a604259af47419369fbdc3

.zuul.yaml

@@ -274,6 +274,16 @@
               - ^setup.cfg$
               - ^tempest/hacking/.*$
               - ^tempest/tests/.*$
+        - nova-live-migration:
+            irrelevant-files:
+              - ^(test-|)requirements.txt$
+              - ^.*\.rst$
+              - ^doc/.*$
+              - ^etc/.*$
+              - ^releasenotes/.*$
+              - ^setup.cfg$
+              - ^tempest/hacking/.*$
+              - ^tempest/tests/.*$
     periodic-stable:
       jobs:
         - tempest-full-queens