Update executor ansible on installation

There are two deployment options for the new multi-ansible support:
the executor can install Ansible on startup (the default), or we
can pre-install ansible when we install Zuul, so that it's ready
for the next executor restart.  This change implements the latter.

Change-Id: I0c75724b4376f68128590eaabdd8a10ed63dcda0

manifests/executor.pp

@@ -40,6 +40,13 @@ class zuul::executor (
     }
   }
 
+  exec { 'zuul_manage_ansible':
+    command     => 'zuul-manage-ansible',
+    path        => '/usr/local/bin:/usr/bin:/bin/',
+    subscribe   => Exec['install_zuul'],
+    refreshonly => true,
+  }
+
   include ::pip::python3
 
   exec { 'install-ara-safely':

templates/zuulv3.conf.erb

@@ -56,6 +56,7 @@ git_user_name=<%= @git_name %>
 <% end -%>
 
 [executor]
+manage_ansible=false
 log_config=/etc/zuul/executor-logging.conf
 job_dir=/var/lib/zuul/builds
 <% if @site_variables_yaml_file != nil -%>