ZTS: Another round of changes for FreeBSD

ZTS: Another round of changes for FreeBSD

Highlights:
* is_linux -> is_illumos swaps
* make block_device_wait more clever when paths are given
* slightly optimize default_cleanup_noexit
* remove platform differences in user_run
* temporarily expect non-libfetch behavior for keylocation=/foo/bar
* fix sharenfs exceptions
* don't test multihost property
* fix misc broken platform checks
* clear zinjected faults in removal_resume_export callback

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: John Kennedy <john.kennedy@delphix.com>
Signed-off-by: Ryan Moeller <ryan@iXsystems.com>
Closes #10092