FIX: do not show send pm prompt when user cant pm (#25912)

Prior to this fix even when the user was not part of a group allowing sending pm we would show the prompt: "You've replied to ... X times, did you know you could send them a personal message instead?"

lib/composer_messages_finder.rb

@@ -181,6 +181,7 @@ class ComposerMessagesFinder
   end
 
   def check_get_a_room(min_users_posted: 5)
+    return unless @user.guardian.can_send_private_messages?
     return unless educate_reply?(:notified_about_get_a_room)
     return unless @details[:post_id].present?
     return if @topic.category&.read_restricted