Cleanup system-required stragglers

A few projects got thorugh with the merging and rebasing races. Clean
these up as they don't need explicit system-required templates anymore.

Change-Id: I4f99b3b5f315bbcd6d173603cd250931b56b893d

zuul.d/projects.yaml

@@ -4759,7 +4759,6 @@
 - project:
     name: openstack/fenix
     templates:
-      - system-required
       - noop-jobs
 
 - project:
@@ -10564,11 +10563,6 @@
     templates:
       - build-only-specs-jobs
 
-- project:
-    name: openstack/openstack-service-broker
-    templates:
-      - system-required
-
 - project:
     name: openstack/openstack-spaceport
     templates:
@@ -11510,7 +11504,6 @@
 - project:
     name: openstack/puppet-fenix
     templates:
-      - system-required
       - noop-jobs
 
 - project:
@@ -12068,7 +12061,6 @@
 - project:
     name: openstack/python-fenixclient
     templates:
-      - system-required
       - noop-jobs
 
 - project: