[BUGFIX] Revert "[TASK] Use a 401 header if login is not successful"

This reverts commit 70ce5402ad9f1a8a98c7014e6ce5af79d9b7a4de.

The 401 header code is used with HTTP based authentication schemes,
based on RFC 2617.

This is not the case here.

Resolves: #55966
Reverts: #51803
Releases: 6.2, 6.1, 6.0, 4.5
Change-Id: Id283069003542ea5b44fdd72b7abda88a2b6762d
Reviewed-on: https://review.typo3.org/27900
Reviewed-by: Markus Klein
Tested-by: Markus Klein