Fix ZTS Amazon 2 failures
Fix ZTS Amazon 2 failures

The Amazon Linux 2 AMI includes a udev rule which creates symlinks
from /dev/sda to /dev/xvda in order to "maintain a consistent naming
scheme".  This conflicts with the names assigned to real scsi_debug
device resulting in test failures.  Therefore, the rule which creates
these aliases must be removed when bootstrapping the instance for
ZTS testing.

Signed-off-by: Brian Behlendorf <32d50ad1e384dcb9a5bf7e40fa470df5dabaf348@llnl.gov>

gmelikov/zfs-buildbot,zfsonlinux/zfs-buildbot,gmelikov/zfs-buildbot,zfsonlinux/zfs-buildbot