puppet: Move ssh configuration to use notify.

This handles more correctly the case where we're using the upstream
sshd_config file.

puppet/zulip_ops/manifests/base.pp

@@ -81,6 +81,10 @@ class zulip_ops::base {
     mode       => 644,
   }
 
+  service { 'ssh':
+    ensure     => running,
+  }
+
   if $zulip::base::release_name == "xenial" {
     # Our custom sshd_config uses options that don't exist on trusty.
     file { '/etc/ssh/sshd_config':
@@ -90,14 +94,10 @@ class zulip_ops::base {
       owner      => 'root',
       group      => 'root',
       mode       => 644,
+      notify     => Service['ssh'],
     }
   }
 
-  service { 'ssh':
-    ensure     => running,
-    subscribe  => File['/etc/ssh/sshd_config'],
-  }
-
   file { '/root/.emacs':
     ensure     => file,
     mode       => 600,