Eliminate unnecessary UFS1 integrity checks.

The UFS1 integrity checks added in FreeBSD 14 were too aggressive
for UFS1 filesystems created in FreeBSD 4 and 9 systems. This patch
removes those tests which can be done safely since they are not
relevant to the current implementation of UFS1.

This is a follow-on report to bug report 264450 (comments 21-28).

Reported by: slb@sonnet.com
Tested by: slb@sonnet.com
PR: 264450
MFC after: 1 week