* Move a-b to PSR-4
* Move c-d to PSR-4
* Move e+g to PSR-4
* Move h-l to PSR-4
* Move m-r to PSR-4
* Move s-u to PSR-4
* Move files/ to PSR-4
* Move remaining tests to PSR-4
* Remove Test\ from old autoloader
Fixes #22119
Just try to get the folder of the user. If it is not there a
NotFoundException will be thrown. Which will be handled by the avatar
endpoint.