discourse: Make sure the notification email setting applies

Discourse normally overrides the default notification email setting,
which makes the `notificationEmailAddress` setting ineffective. Add a
patch to remove this override.

Fixes #140114.

pkgs/servers/web-apps/discourse/default.nix

@@ -263,6 +263,9 @@ let
       # defaults to the plugin's directory and isn't writable at the
       # time of asset generation
       ./auto_generated_path.patch
+
+      # Make sure the notification email setting applies
+      ./notification_email.patch
     ];
 
     postPatch = ''

pkgs/servers/web-apps/discourse/notification_email.patch

@@ -0,0 +1,18 @@
+diff --git a/db/fixtures/990_settings.rb b/db/fixtures/990_settings.rb
+deleted file mode 100644
+index 6f21e58813..0000000000
+--- a/db/fixtures/990_settings.rb
++++ /dev/null
+@@ -1,12 +0,0 @@
+-# frozen_string_literal: true
+-
+-if SiteSetting.notification_email == SiteSetting.defaults[:notification_email]
+-  # don't crash for invalid hostname, which is possible in dev
+-  begin
+-    SiteSetting.notification_email = "noreply@#{Discourse.current_hostname}"
+-  rescue Discourse::InvalidParameters
+-    if Rails.env.production?
+-      STDERR.puts "WARNING: Discourse hostname: #{Discourse.current_hostname} is not a valid domain for emails!"
+-    end
+-  end
+-end