Revert "project-config-grafana: make opendev-buildset-registry soft dep"

This reverts commit ace49f32d9.

This job calls use-buildset-registry which needs a registry running to
work.  We think this is basically as designed;
https://review.opendev.org/#/q/I74c771d048c7a808511864445ed1a124644f661a
adds this to project-config.  Since we've decided this is a hard
dependency, revert this change.

Change-Id: Id07f728b8414d29f107ee2d00590d417d20867e5

zuul.d/jobs.yaml

@@ -1296,7 +1296,6 @@
       - openstack/project-config
     dependencies:
       - name: opendev-buildset-registry
-        soft: true
       - name: grafyaml-build-image
         soft: true