CAM timeouts on boot (13.0-p8, Dell R730xd, mrsas controller)

I upgraded 12.2 to 13.0-p8 and hit a delay with SCSI drive
initialisation, it loops for a timeout over the "Waiting for CAM"
message, then proceeds.

This interferes with the ZFS initialisation and the non-root zpool are
not imported.

I intruded a  /usr/local/etc/rc.d script PROCEED: var REQUIRE: zfs
which put it right after zfs initialisation, before any daemons, and I
can manually zpool import the tank once the SCSI stuff has settled
down.

Adding delay to loader.conf CAM initialisation didn't fix this.

There are references to this in 2018-2020 timeframe, but mostly it's
people on desktops. I am not used to Dell rackmounts going this bad.

-G