ZTS: zfs_list_004_neg should not check paths that belong to ZFS

When ZFS is on root, /tmp is a ZFS. This causes zfs_list_004_neg to
fail since zfs list on /tmp passes when the test expects it not to.
The fix is to exclude paths that belong to ZFS.

Reviewed-by: John Kennedy <john.kennedy@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Palash Gandhi <pbg4930@rit.edu>
Closes #12744