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

This reverts commit b0c54dcadfba635d44242ce3778bbf8486e9b33e.

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: I81e0e2bb428a9da69155fc597933bd9f023cf226
Reviewed-on: https://review.typo3.org/27898
Reviewed-by: Markus Klein
Tested-by: Markus Klein