Add rolling upgrade job coming from bobcat

Also clean up a couple jobs for rocky and stein; those were dropped
a while ago; it's not clear why it didn't cause some sort of error
before.

Related-Change: Ibe46aecf0f4461be59eb206bfe9063cc1bfff706
Change-Id: Ia94d4b63e5c97e75656cdf7be044b3ec2c7813e7

.zuul.yaml

@@ -539,6 +539,12 @@
     vars:
       previous_swift_version: origin/stable/2023.1
 
+- job:
+    name: swift-multinode-rolling-upgrade-bobcat
+    parent: swift-multinode-rolling-upgrade
+    vars:
+      previous_swift_version: origin/stable/2023.2
+
 - job:
     name: swift-multinode-rolling-upgrade-master
     parent: swift-multinode-rolling-upgrade
@@ -853,8 +859,6 @@
         - swift-tox-func-py39-centos-9-stream
         - swift-tox-func-encryption-py39-centos-9-stream
         - swift-tox-func-ec-py39-centos-9-stream
-        - swift-multinode-rolling-upgrade-rocky
-        - swift-multinode-rolling-upgrade-stein
         - swift-multinode-rolling-upgrade-train
         - swift-multinode-rolling-upgrade-ussuri
         - swift-multinode-rolling-upgrade-victoria
@@ -863,6 +867,7 @@
         - swift-multinode-rolling-upgrade-yoga
         - swift-multinode-rolling-upgrade-zed
         - swift-multinode-rolling-upgrade-antelope
+        - swift-multinode-rolling-upgrade-bobcat
         - swift-multinode-rolling-upgrade-master:
             branches: master