[TASK] Retry request on 403 in linkvalidator

When the linkvalidator detects a 403 error when doing a HEAD request to
an external URL it will retry the request using the GET method.

Resolves: #54513
Releases: 6.2
Change-Id: Ib36b6cbb8e981b95c348afd5a063ca4f5040de75
Reviewed-on: https://review.typo3.org/26489
Reviewed-by: Markus Klein
Tested-by: Markus Klein