Add publish amphora image job for Jammy

The job definition was added earlier by [1], but it was not actually
enabled.

[1] 37ddc6fba4

Change-Id: Ia51db61bf9d3effdad99532ea62f38ed2e8dd995

zuul.d/projects.yaml

@@ -126,6 +126,10 @@
             branches:
               regex: ^stable/.*$
               negate: true
+        - publish-openstack-octavia-amphora-image-jammy:
+            branches:
+              regex: ^stable/.*$
+              negate: true
         - publish-openstack-octavia-amphora-image-centos-9-stream:
             branches:
               regex: ^stable/.*$