Revert "Fix EZP-23234: provide a default (null) locationId for the internal _ezpublishLocation route"

This reverts commit 2a53c3f719250e428b8e6361366d4398e78985ee.
Fix EZP-23234: Language Switcher using sub-requests throws an exception in preview

https://jira.ez.no/browse/EZP-23234
Alternative approach to #950 (already merged) which should fix the leftovers.
Merge pull request #986 from ezsystems/fix_EZP-23234_languageSwitcherPreview

Fix EZP-23234: Language Switcher using sub-requests throws an exception in preview