Stop running project-config-dib

We're about to remove all of the DIB config from this repo; stop
running the job that validates it.

Change-Id: Ia97beb658ddec372eae9c86fa61e5bba92ca31d0

zuul.d/projects.yaml

@@ -3492,7 +3492,6 @@
               - other-requirements.txt
               - tox.ini
         - openstack-zuul-jobs-linters
-        - project-config-dib
         - project-config-gerrit
         - project-config-grafana:
             files: *project-config-grafana-files
@@ -3513,7 +3512,6 @@
         - build-openstack-specs-site:
             files: *specs-site
         - openstack-zuul-jobs-linters
-        - project-config-dib
         - project-config-gerrit
         - project-config-grafana:
             files: *project-config-grafana-files