Add support for multilingual properties to EntityFieldQuery

In #1658712: Refactor test_entity schema to be multilingual we started paving the way for adding multilingual support to entity properties as planned in #1498634: [meta] Define revision/translation SQL schema for core entities (no patch). We already have a change notice for that as this approach is going to be extended to all core entities.

#1184272: Remove deprecated $conditions support from entity controller already needs EFQ to have multilingual property conditions to make EntityTest work correctly. By removing the custom solution introduced there in EntityTestStorageController::loadByProperties() and making the already existing tests pass, we would ensure that we already have pretty solid multilingual capablities for property conditions.