[FEATURE] Set tabindex of honeypot to negative value

Resolves: #59832
Releases: 6.1, 4.7, 4.5
Change-Id: Id2fc96ee296c43a17db6322ee6607f71e3c8f2ac
Reviewed-on: https://review.typo3.org/31741
Reviewed-by: Ralf Zimmermann <ralf.zimmermann@tritum.de>
Tested-by: Ralf Zimmermann <ralf.zimmermann@tritum.de>