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

This reverts commit 40cb0a435e31dd0378151ce6613ad54c8e7d075b.

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: I279e98d8e756bbbbaae6d387a84328b84fb23388
Reviewed-on: https://review.typo3.org/27899
Reviewed-by: Markus Klein
Tested-by: Markus Klein