Fix EZP-20677: Removing users do not clean up ezuser table and urlaliases

This PR fixes issue https://jira.ez.no/browse/EZP-20677

The issue has two parts:

1. ```UserService::deleteUser()``` did not call ```UserHandler::delete()```, which resulted in user data (```ezuser``` table in Legacy Storage) not being removed
2. ```ContentService::deleteContent()``` did not call ```UrlAliasHandler::locationDeleted()```, resulting in URL aliases for Locations of deleted Content not being disabled

Tests for updated methods are implemented in ```Core\Repository\Tests\Service\Mock```, existing tests duplicated in integration suite are removed.

Additional:
* after removing User data, SPI cache for corresponding Content is invalidated