Remove puppet 3 jobs from master

We no longer support puppet 3 on master branches, as such, we can
start to remove these jobs from .zuul.yaml.

This will help reduce the amount of jobs we need to carry on branches.

Change-Id: I31d790121c8eab7ff50dc579727a028b74b463d5
Signed-off-by: Paul Belanger <pabelanger@redhat.com>

.zuul.yaml

@@ -331,13 +331,6 @@
       - ^releasenotes/.*$
       - ^test-requirements.txt$
 
-- job:
-    name: puppet-openstack-syntax-3-legacy
-    parent: puppet-openstack-syntax
-    branches: ^(stable/(newton|ocata)).*$
-    vars:
-      puppet: 3
-
 - job:
     name: puppet-openstack-syntax-4
     parent: puppet-openstack-syntax
@@ -359,22 +352,6 @@
       - ^releasenotes/.*$
       - ^test-requirements.txt$
 
-- job:
-    name: puppet-openstack-unit-3.6-centos-7
-    parent: puppet-openstack-unit-base
-    nodeset: centos-7
-    branches: ^(stable/(newton|ocata)).*$
-    vars:
-      puppet_gem_version: 3.6
-
-- job:
-    name: puppet-openstack-unit-3.8-centos-7
-    parent: puppet-openstack-unit-base
-    nodeset: centos-7
-    branches: ^(stable/(newton|ocata)).*$
-    vars:
-      puppet_gem_version: 3.8
-
 - job:
     name: puppet-openstack-unit-4.8-centos-7
     parent: puppet-openstack-unit-base
@@ -395,14 +372,10 @@
     name: puppet-openstack-module-unit-jobs
     check:
       jobs:
-        - puppet-openstack-unit-3.6-centos-7
-        - puppet-openstack-unit-3.8-centos-7
         - puppet-openstack-unit-4.8-centos-7
         - puppet-openstack-unit-latest-centos-7
     gate:
       jobs:
-        - puppet-openstack-unit-3.6-centos-7
-        - puppet-openstack-unit-3.8-centos-7
         - puppet-openstack-unit-4.8-centos-7
 
 - project-template:
@@ -410,12 +383,10 @@
     check:
       jobs:
         - puppet-openstack-lint
-        - puppet-openstack-syntax-3-legacy
         - puppet-openstack-syntax-4
     gate:
       jobs:
         - puppet-openstack-lint
-        - puppet-openstack-syntax-3-legacy
         - puppet-openstack-syntax-4
 
 - project: