fix empty repo updated time (#33120)

fixes #33119 

routers/web/repo/view_home.go

![image](https://github.com/user-attachments/assets/b0d6c5f5-7abc-478a-8d41-4b44dbd460aa)

Calling `updateContextRepoEmptyAndStatus` will always ask the DB to
update the updated Unix attributes.
When revisiting the repo's home page, the timestamp will be updated
unexpectedly, so I added the needsUpdate variable to check whether, in
the end, the commitment to db update is necessary if columns have not
changed at all.

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

models/repo/update.go

@@ -46,6 +46,12 @@ func UpdateRepositoryCols(ctx context.Context, repo *Repository, cols ...string)
 	return err
 }
 
+// UpdateRepositoryColsNoAutoTime updates repository's columns and but applies time change automatically
+func UpdateRepositoryColsNoAutoTime(ctx context.Context, repo *Repository, cols ...string) error {
+	_, err := db.GetEngine(ctx).ID(repo.ID).Cols(cols...).NoAutoTime().Update(repo)
+	return err
+}
+
 // ErrReachLimitOfRepo represents a "ReachLimitOfRepo" kind of error.
 type ErrReachLimitOfRepo struct {
 	Limit int