In order to determine whether HTTP referrer headers would be submitted
to server-side backend API, a corresponding "reload" was triggered for
the backend's main login form.

Since the behavior resulted in reduced user experience, the refreshing
mechanism was replaced by an equivalent AJAX endpoint and request.

Resolves: #92293
Releases: master, 10.4, 9.5
Change-Id: I745d266a97135496276437b8eaf9dd206bc5806e
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/69336


Tested-by: core-ci <typo3@b13.com>
Tested-by: Michael Telgkamp <michael.telgkamp@mindscreen.de>
Tested-by: Benjamin Franzke <bfr@qbus.de>
Reviewed-by: Michael Telgkamp <michael.telgkamp@mindscreen.de>
Reviewed-by: Benjamin Franzke <bfr@qbus.de>