Consider using `lazy_object_proxy` for `service_locator` to simplify resetting the test environment

[janbuchar]

If service_locator was a lazy_object_proxy, we could just re-set crawlee._service_locator.service_locator to a new instance of ServiceLocator and we wouldn't need to do this here and in crawlee tests (code duplication across different packages is kinda painful)

Originally posted by @janbuchar in apify/apify-sdk-python#355 (comment)

[vdusek]

Maybe we can close this since @Pijukatel reworked the service locator and instance caching, and the test reset in conftest is simpler. What do you think, @janbuchar?