Require explicit list of publishers for each job

Publisher are required for almost every job and it's very easy to forget
to specify them and get a job that cannot be debugged. If publishers are
not required for a job, one should explicitely specify empty list of
publishers as I did here for test job and for rtfd hook.

Change-Id: I7c4923910b0e139ca3831b6450b0fbb82b618b64

jenkins/jobs/misc.yaml

@@ -9,6 +9,7 @@
 
     builders:
       - shell: 'echo ok'
+    publishers: []
 
 - job-template:
     name: 'gate-{name}-run-tests'