Add openstacksdk functional job to devstack pipelines

openstacksdk gates on the new-style devstack functional base jobs. It
serves as a good test case to make sure the functional base jobs don't
break.

Change-Id: I817639ed30cda8ea51d156872a14bbcf10a4e63d

Author: emonty

.zuul.yaml

@@ -621,6 +621,10 @@
             irrelevant-files:
               - ^.*\.rst$
               - ^doc/.*$
+        - openstacksdk-functional-devstack:
+            irrelevant-files:
+              - ^.*\.rst$
+              - ^doc/.*$
     gate:
       jobs:
         - devstack
@@ -641,6 +645,10 @@
             irrelevant-files:
               - ^.*\.rst$
               - ^doc/.*$
+        - openstacksdk-functional-devstack:
+            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.