[TASK] Obsolete code in saltedpasswords

tx_saltedpasswords_autoloader was used in old install tool only
and is obsolete now.

Change-Id: If398a197a18bfda20789afd0aa0104fcd8ba5993
Resolves: #55446
Releases: 6.2
Reviewed-on: https://review.typo3.org/27138
Reviewed-by: Thomas Maroschik
Reviewed-by: Marcin Sągol
Reviewed-by: Wouter Wolters
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn