Send deleted posts on getPostSince when collapsed threads is enabled (#20976)

store/sqlstore/post_store.go

@@ -1226,7 +1226,6 @@ func (s *SqlPostStore) getPostsSinceCollapsedThreads(options model.GetPostsSince
 		From("Posts").
 		LeftJoin("Threads ON Threads.PostId = Posts.Id").
 		LeftJoin("ThreadMemberships ON ThreadMemberships.PostId = Posts.Id AND ThreadMemberships.UserId = ?", options.UserId).
-		Where(sq.Eq{"Posts.DeleteAt": 0}).
 		Where(sq.Eq{"Posts.ChannelId": options.ChannelId}).
 		Where(sq.Gt{"Posts.UpdateAt": options.Time}).
 		Where(sq.Eq{"Posts.RootId": ""}).