[stable-only] Specify openstacksdk stable branch

Taking the advice given here:
http://lists.openstack.org/pipermail/openstack-discuss/2022-January/026905.html
to fix the openstacksdk-functional-devstack job.

This job is not specified in glance's .zuul.yaml, but is brought in
by the integrated-gate-storage template:
86db21ea6a/zuul.d/integrated-gate.yaml (L382-L398)

So we add the job here so that we can override its definition.

Change-Id: I8f1f38df4746cced085fb1cb4e96540763cdda13
(cherry picked from commit b76dd7880c)
(cherry picked from commit fdf7b80daf)
(cherry picked from commit 78d63ec150)

.zuul.yaml

@@ -240,6 +240,11 @@
             irrelevant-files: *tempest-irrelevant-files
         - tempest-ipv6-only:
             irrelevant-files: *tempest-irrelevant-files
+        - openstacksdk-functional-devstack:
+            required-projects:
+            - name: opendev.org/openstack/openstacksdk
+              override-branch: stable/ussuri
+            irrelevant-files: *tempest-irrelevant-files
 
     gate:
       jobs:
@@ -251,6 +256,11 @@
             irrelevant-files: *tempest-irrelevant-files
         - tempest-ipv6-only:
             irrelevant-files: *tempest-irrelevant-files
+        - openstacksdk-functional-devstack:
+            required-projects:
+            - name: opendev.org/openstack/openstacksdk
+              override-branch: stable/ussuri
+            irrelevant-files: *tempest-irrelevant-files
     experimental:
       jobs:
         - glance-tox-py37-glance_store-tips