cli: set exit_on_failure for all CLI classes (#9094)

lib/mastodon/settings_cli.rb

@@ -6,6 +6,9 @@ require_relative 'cli_helper'
 
 module Mastodon
   class RegistrationsCLI < Thor
+    def self.exit_on_failure?
+      true
+    end
     desc 'open', 'Open registrations'
     def open
       Setting.open_registrations = true