nginx: Move uploads handling into app_frontend_base.

As uploads are a feature of the application, not of a generic nginx
deployment, move them into the `zulip::app_frontend_base` class.  This
is purely for organizational clarity -- we do not support deployments
with has `zulip::nginx` but not `zulip::app_frontend_base`.

puppet/zulip/manifests/app_frontend_base.pp

@@ -69,6 +69,40 @@ class zulip::app_frontend_base {
     notify  => Service['nginx'],
   }
 
+  # Configuration for how uploaded files and profile pictures are
+  # served.  The default is to serve uploads using using the `nginx`
+  # `internal` feature via django-sendfile2, which basically does an
+  # internal redirect and returns the file content from nginx in an
+  # HttpResponse that would otherwise have been a redirect.  Profile
+  # pictures are served directly off disk.
+  #
+  # For installations using S3 to serve uploaded files, we want Django
+  # to handle the /serve_uploads and /user_avatars routes, so that it
+  # can serve a redirect (after doing authentication, for uploads).
+  $no_serve_uploads = zulipconf('application_server', 'no_serve_uploads', false)
+  if $no_serve_uploads {
+    file { '/etc/nginx/zulip-include/app.d/uploads-internal.conf':
+      ensure  => absent,
+    }
+  } else {
+    file { '/etc/nginx/zulip-include/app.d/uploads-internal.conf':
+      ensure  => file,
+      require => Package[$zulip::common::nginx],
+      owner   => 'root',
+      group   => 'root',
+      mode    => '0644',
+      notify  => Service['nginx'],
+      source  => 'puppet:///modules/zulip/nginx/zulip-include-maybe/uploads-internal.conf',
+    }
+  }
+
+  # TODO/compatibility: Removed 2021-04 in Zulip 4.0; these lines can
+  # be removed once one must have upgraded through Zulip 4.0 or higher
+  # to get to the next release.
+  file { ['/etc/nginx/zulip-include/uploads.route', '/etc/nginx/zulip-include/app.d/thumbor.conf']:
+    ensure => absent,
+  }
+
   # This determines whether we run queue processors multithreaded or
   # multiprocess.  Multiprocess scales much better, but requires more
   # RAM; we just auto-detect based on available system RAM.

puppet/zulip/manifests/nginx.pp

@@ -29,47 +29,6 @@ class zulip::nginx {
     notify  => Service['nginx'],
   }
 
-  # Configuration for how uploaded files and profile pictures are
-  # served.  The default is to serve uploads using using the `nginx`
-  # `internal` feature via django-sendfile2, which basically does an
-  # internal redirect and returns the file content from nginx in an
-  # HttpResponse that would otherwise have been a redirect.  Profile
-  # pictures are served directly off disk.
-  #
-  # For installations using S3 to serve uploaded files, we want Django
-  # to handle the /serve_uploads and /user_avatars routes, so that it
-  # can serve a redirect (after doing authentication, for uploads).
-  $no_serve_uploads = zulipconf('application_server', 'no_serve_uploads', false)
-  if $no_serve_uploads {
-    file { '/etc/nginx/zulip-include/app.d/uploads-internal.conf':
-      ensure  => absent,
-    }
-  } else {
-    file { '/etc/nginx/zulip-include/app.d/uploads-internal.conf':
-      ensure  => file,
-      require => Package[$zulip::common::nginx],
-      owner   => 'root',
-      group   => 'root',
-      mode    => '0644',
-      notify  => Service['nginx'],
-      source  => 'puppet:///modules/zulip/nginx/zulip-include-maybe/uploads-internal.conf',
-    }
-  }
-
-  # TODO/compatibility: Removed 2021-04 in Zulip 4.0; these lines can
-  # be removed once one must have upgraded through Zulip 4.0 or higher
-  # to get to the next release.
-  file { '/etc/nginx/zulip-include/uploads.route':
-    ensure  => absent,
-  }
-
-  # TODO/compatibility: Removed 2021-05 in Zulip 4.0; these lines can
-  # be removed once one must have upgraded through Zulip 4.0 or higher
-  # to get to the next release.
-  file { '/etc/nginx/zulip-include/app.d/thumbor.conf':
-    ensure  => absent,
-  }
-
   file { '/etc/nginx/dhparam.pem':
     ensure  => file,
     require => Package[$zulip::common::nginx],