[BUGFIX] Use HTTP 400 instead of 500 when client is faulty

When checking for precondition in the request, HTTP 400 code should
be returned whenever the client is responsible for having issued a
bad request.

HTTP 500 indicates an internal error on the server, which is not the
case under such circumstance.

Change-Id: Ib7e63428b1a84b63e1a2a0c9d95513972be83d33
Resolves: #81941
Releases: master, 8.7
Reviewed-on: https://review.typo3.org/53564


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Markus Klein <markus.klein@typo3.org>
Reviewed-by: Helmut Hummel <typo3@helhum.io>
Reviewed-by: Joerg Boesche <typo3@joergboesche.de>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Andreas Fernandez <typo3@scripting-base.de>
Tested-by: Andreas Fernandez <typo3@scripting-base.de>