fix https://github.com/FreshRSS/FreshRSS/issues/8252
regression from https://github.com/FreshRSS/FreshRSS/pull/6957
The current code works with MySQL 8+ (as well as PostgreSQL and SQLite), but not with MariaDB, because MariaDB does not support CTE (Common Table Expression) fully (which I was not aware of)...
* Change SQL update query for MariaDB / MySQL
fix https://github.com/FreshRSS/FreshRSS/issues/5707
* No change for SQLite
* Fix merge error
* Update MySQL version on the model of PostgreSQL
Performance to be tested
* Fix LEFT JOIN, also for PostgreSQL / SQLite
* Fix alias
* Reduce MySQL deadlock
* Fix compatibility with SQLite
* Back to identical SQL for all databases
* Stable IDs during SQL import
Follow-up of https://github.com/FreshRSS/FreshRSS/pull/7949
Make sure that the original category IDs, feed IDs, and label IDs are kept identical during an SQL import.
Avoid breaking everything referring to categories, feeds, labels by their IDs such as searches and third-party extensions.
* Fix export of default category