WIP removing SAS phy control from the ZFS test suite

Convert zfsd_replace_001_pos to use libgnop

tests/sys/cddl/zfs/tests/zfsd/zfsd_replace_001_pos.ksh
tests/sys/cddl/zfs/tests/zfsd/zfsd_test.sh

• Simulate disk failures with gnop, not SAS phy control
• Fix the log_assert message
• Reduce the disk count to 3
• Reduce the runtime by removing excessive I/O

Sponsored by: Spectra Logic Corp