Pin jenkins jobs of groups portal to precise

The groups portal based on Drupal 7.x and as some trusty php
packages is buggy, so we need to do a careful testing before
we can switch from php 5.3 to php 5.5.

Change-Id: I3e42448a8c245a30e8b5b617b345d061afb4e34d

modules/openstack_project/files/jenkins_job_builder/config/groups.yaml

@@ -1,6 +1,6 @@
 - job:
     name: gate-groups-unittests
-    node: 'bare-precise || bare-trusty'
+    node: 'bare-precise'
 
     builders:
         - revoke-sudo

modules/openstack_project/files/jenkins_job_builder/config/projects.yaml

@@ -2920,7 +2920,7 @@
 
 - project:
     name: groups
-    node: 'bare-precise || bare-trusty'
+    node: 'bare-precise'
     tarball-site: tarballs.openstack.org
 
     jobs:

modules/openstack_project/files/zuul/layout.yaml

@@ -480,6 +480,9 @@ jobs:
   # openstackid doesn't work with php5-mcrypt on trusty
   - name: ^.*openstackid-(unittests|release).*$
     parameter-function: set_node_options_default_precise
+  # groups works with php5.3 on precise
+  - name: ^.*groups-(unittests|release).*$
+    parameter-function: set_node_options_default_precise
   # tempest and d-g branchless tests need to only run on master
   # (needs to be early to not impact non-voting stanzas later)
   - name: ^(?!periodic-).*(-icehouse|-havana)$