upgrade-postgresql: Use tags to partially-apply configuration.

This uses the same technique used in 840884ec89, to only apply select
parts of the Puppet configuration.  This is more correct, and simpler,
than attempting to chop out some base puppet roles, and hack around
the `purge => true` supervisor.d configuration.

(cherry picked from commit e13f82f048)

puppet/zulip/manifests/postgresql_base.pp

@@ -47,12 +47,13 @@ class zulip::postgresql_base {
     ensure  => link,
     require => Package[$postgresql],
     target  => $postgresql_dict_dict,
+    tag     => ['postgresql_upgrade'],
   }
   file { "${tsearch_datadir}/en_us.affix":
     ensure  => link,
     require => Package[$postgresql],
     target  => $postgresql_dict_affix,
-
+    tag     => ['postgresql_upgrade'],
   }
   file { "${tsearch_datadir}/zulip_english.stop":
     ensure  => file,
@@ -61,6 +62,7 @@ class zulip::postgresql_base {
     group   => 'root',
     mode    => '0644',
     source  => 'puppet:///modules/zulip/postgresql/zulip_english.stop',
+    tag     => ['postgresql_upgrade'],
   }
   zulip::nagios_plugins { 'zulip_postgresql': }
 
@@ -73,6 +75,7 @@ class zulip::postgresql_base {
         Package[$postgresql],
         Exec[$setup_system_deps]
       ],
+      tag     => ['postgresql_upgrade'],
     }
     exec { 'pgroonga-config':
       require => Package["${postgresql}-pgdg-pgroonga"],

puppet/zulip/manifests/postgresql_common.pp

@@ -61,6 +61,7 @@ class zulip::postgresql_common {
   zulip::safepackage { $postgresql_packages:
     ensure  => installed,
     require => Exec['generate-default-snakeoil'],
+    tag     => ['postgresql_upgrade'],
   }
 
   if $facts['os']['family'] == 'Debian' {

puppet/zulip/manifests/supervisor.pp

@@ -12,15 +12,12 @@ class zulip::supervisor {
   }
 
   $conf_dir = $zulip::common::supervisor_conf_dir
-  # lint:ignore:quoted_booleans
-  $should_purge = $facts['leave_supervisor'] != 'true'
-  # lint:endignore
   file { $conf_dir:
     ensure  => directory,
     require => Package['supervisor'],
     owner   => 'root',
     group   => 'root',
-    purge   => $should_purge,
+    purge   => true,
     recurse => true,
     notify  => Service[$supervisor_service],
   }