Fix EZP-22055: A partial pathString will load a REST location

Fixes https://jira.ez.no/browse/EZP-22055.

REST uses the pathString to load a locationId, unlike the Public API, to ensure locations unicity.

The loading code was only considering the last number of the path string, making all previous parts useless. With this patch, a 404 will be returned if the path string parameter doesn't match the loaded location's path string.