MM-20681 Fix custom post types not marking channel unread when using Mark as Unread (#13247)

* MM-20681 Fix custom post types not marking channel unread when using Mark as Unread

* Fix inverted if statements

store/sqlstore/post_store.go

@@ -102,11 +102,7 @@ func (s *SqlPostStore) Save(post *model.Post) (*model.Post, *model.AppError) {
 
 	time := post.UpdateAt
 
-	if post.Type != model.POST_JOIN_LEAVE && post.Type != model.POST_ADD_REMOVE &&
-		post.Type != model.POST_JOIN_CHANNEL && post.Type != model.POST_LEAVE_CHANNEL &&
-		post.Type != model.POST_JOIN_TEAM && post.Type != model.POST_LEAVE_TEAM &&
-		post.Type != model.POST_ADD_TO_CHANNEL && post.Type != model.POST_REMOVE_FROM_CHANNEL &&
-		post.Type != model.POST_ADD_TO_TEAM && post.Type != model.POST_REMOVE_FROM_TEAM {
+	if !post.IsJoinLeaveMessage() {
 		if _, err := s.GetMaster().Exec("UPDATE Channels SET LastPostAt = GREATEST(:LastPostAt, LastPostAt), TotalMsgCount = TotalMsgCount + 1 WHERE Id = :ChannelId", map[string]interface{}{"LastPostAt": time, "ChannelId": post.ChannelId}); err != nil {
 			mlog.Error("Error updating Channel LastPostAt.", mlog.Err(err))
 		}
@@ -203,7 +199,7 @@ func (s *SqlPostStore) GetFlaggedPostsForTeam(userId, teamId string, offset int,
 
 	query := `
             SELECT
-                A.*, (SELECT count(Posts.Id) FROM Posts WHERE Posts.RootId = A.Id AND Posts.DeleteAt = 0) as ReplyCount 
+                A.*, (SELECT count(Posts.Id) FROM Posts WHERE Posts.RootId = A.Id AND Posts.DeleteAt = 0) as ReplyCount
             FROM
                 (SELECT
                     *
@@ -245,7 +241,7 @@ func (s *SqlPostStore) GetFlaggedPostsForChannel(userId, channelId string, offse
 	var posts []*model.Post
 	query := `
 		SELECT
-			*, (SELECT count(Posts.Id) FROM Posts WHERE Posts.RootId = p.Id AND Posts.DeleteAt = 0) as ReplyCount 
+			*, (SELECT count(Posts.Id) FROM Posts WHERE Posts.RootId = p.Id AND Posts.DeleteAt = 0) as ReplyCount
 		FROM Posts p
 		WHERE
 			Id IN (SELECT Name FROM Preferences WHERE UserId = :UserId AND Category = :Category)