Problem 1:
- open widget on legacy cms (same domain as tocco) with differen language than users language
- open backoffice (new client)
- => Problem with locale (user vs. widget locale)

Problem 2:
- open entity detail
- logout and login with user with different locale
- => Problem with locale on breadcrumbs and relations view

Refs: BS-8895, TOCDEV-6276
Changelog: fix caching and intl race condition
Cherry-pick: Up