Don't use branch matching

This is not needed since we have implicit branch matches - and even
hurts since the master version is used on stable branches

Remove here - this ensures that future stable branches and master are
fine.

Change-Id: I24a46d0d7476203feccb1250d4ce3ad94b2e0ecd
(cherry picked from commit be537bb79c)

.zuul.yaml

@@ -1,7 +1,5 @@
 - job:
     name: barbican-devstack-functional-base
-    # start running with Pike
-    branches: ^(?!stable/ocata).*$
     parent: legacy-dsvm-base
     vars:
       database: sql
@@ -148,8 +146,6 @@
 - job:
     name: grenade-devstack-barbican
     parent: legacy-dsvm-base
-    # Start testing with pike
-    branches: ^(?!stable/ocata).*$
     irrelevant-files:
       - ^(test-|)requirements.txt$
       - ^setup.cfg$