Anonymous roles resolution and user role deduplication are now performed during authentication instead of authorization. The change ensures:
* If anonymous access is enabled, user will be able to see the anonymous roles added in the roles field in the /_security/_authenticate response.
* Any duplication in user roles are removed and will not show in the above authenticate response.
* In any other case, the response is unchanged.
It also introduces a behaviour change: the anonymous role resolution is now authentication node specific, previously it was authorization node specific. Details can be found at #47195 (comment)