Fix https://github.com/go-gitea/gitea/pull/28547#issuecomment-1867740842
Since https://gitea.com/xorm/xorm/pulls/2383 merged, xorm now supports
UPDATE JOIN.
To keep consistent from different databases, xorm use
`engine.Join().Update`, but the actural generated SQL are different
between different databases.
For MySQL, it's `UPDATE talbe1 JOIN table2 ON join_conditions SET xxx
Where xxx`.
For MSSQL, it's `UPDATE table1 SET xxx FROM TABLE1, TABLE2 WHERE
join_conditions`.
For SQLITE per https://www.sqlite.org/lang_update.html, sqlite support
`UPDATE table1 SET xxx FROM table2 WHERE join conditions` from
3.33.0(2020-8-14).
POSTGRES is the same as SQLITE.
