[BUGFIX] Domain record is not respected

If you have a system which stores sites with different root domains it
is not possible to login from another backend.

Resolves: #50394
Change-Id: Ibae6786219d5517e433b95b18adf5609363aacae
Reviewed-on: https://review.typo3.org/22539
Reviewed-by: Dimitri Koenig
Tested-by: Dimitri Koenig