CI: fix rolling-upgrade jobs

train and ussuri are now EOL; drop them.

yoga has moved from stable to unmaintained.

Change-Id: I3516823fdacbe8fd3c2434c0de9dedd1d82980fe

.zuul.yaml

@@ -490,18 +490,6 @@
     run: tools/playbooks/multinode_setup/run.yaml
     post-run: tools/playbooks/probetests/post.yaml
 
-- job:
-    name: swift-multinode-rolling-upgrade-train
-    parent: swift-multinode-rolling-upgrade
-    vars:
-      previous_swift_version: origin/stable/train
-
-- job:
-    name: swift-multinode-rolling-upgrade-ussuri
-    parent: swift-multinode-rolling-upgrade
-    vars:
-      previous_swift_version: origin/stable/ussuri
-
 - job:
     name: swift-multinode-rolling-upgrade-victoria
     parent: swift-multinode-rolling-upgrade
@@ -524,7 +512,7 @@
     name: swift-multinode-rolling-upgrade-yoga
     parent: swift-multinode-rolling-upgrade
     vars:
-      previous_swift_version: origin/stable/yoga
+      previous_swift_version: origin/unmaintained/yoga
 
 - job:
     name: swift-multinode-rolling-upgrade-zed