FIX: Destroy all posts when hard deleting topic (#17359)

Hard deleting topics that contained soft deleted posts or small actions
used to create orphan posts because only the first post was hard
deleted. This commit adds an error message if there are still posts left
in the topic that must be hard deleted first or hard deletes all small
actions too immediately (there is no other way of hard deleting a small
action because there is no wrench menu).

app/models/topic.rb

@@ -1786,7 +1786,12 @@ class Topic < ActiveRecord::Base
   end
 
   def cannot_permanently_delete_reason(user)
-    if self.posts_count > 0
+    all_posts_count = Post.with_deleted
+      .where(topic_id: self.id)
+      .where(post_type: [Post.types[:regular], Post.types[:moderator_action], Post.types[:whisper]])
+      .count
+
+    if posts_count > 0 || all_posts_count > 1
       I18n.t('post.cannot_permanently_delete.many_posts')
     elsif self.deleted_by_id == user&.id && self.deleted_at >= Post::PERMANENT_DELETE_TIMER.ago
       time_left = RateLimiter.time_left(Post::PERMANENT_DELETE_TIMER.to_i - Time.zone.now.to_i + self.deleted_at.to_i)