Switch project-config to promote jobs [1]: Disable publish

Disable the publish jobs, so that we can change first the build stack
and then write promote jobs without any breakage in between.

Needed-By: https://review.opendev.org/682213
Change-Id: Ia9cb29ff8bd8041aa5f10db146cf22387854a17d

zuul.d/projects.yaml

@@ -3770,10 +3770,12 @@
         - project-config-bindep-fallback-opensuse-15
         - project-config-bindep-fallback-ubuntu-trusty
         - project-config-bindep-fallback-ubuntu-xenial
-    post:
-      jobs:
-        - publish-infra-index
-        - publish-openstack-specs-site
+    # Temporarily disabled to allow us to update them.
+    # TODO(jaegerandi): Enable in promote pipeline.
+    # post:
+    #  jobs:
+    #    - publish-infra-index
+    #    - publish-openstack-specs-site
     periodic:
       jobs:
         - propose-project-config-update