LU-12336 build: Revert Update ZFS version to 0.8.1

LU-12336 build: Revert Update ZFS version to 0.8.1

Revert "LU-12336 build: Update ZFS version to 0.8.1"

We've seen an uptick in autotest testing failures for ZFS
testing and are investigating if moving to ZFS 0.8.1 is a
cause of these failures.  Thus, run the ZFS test sessions
multiple times to get a baseline of test failures with
ZFS 0.7.13.

This reverts commit dba32e417635359b1d68180b77193e1c9ddd1e8f.

Test-Parameters: trivial testgroup=review-dne-zfs-part-1
Test-Parameters: testgroup=review-dne-zfs-part-2
Test-Parameters: testgroup=review-dne-zfs-part-3
Test-Parameters: testgroup=review-dne-zfs-part-4
Test-Parameters: testgroup=review-zfs

Signed-off-by: James Nunez <jnunez@whamcloud.com>
Change-Id: Iedb5c5411c721cfe738a7d3db455b222e7b4050d
Reviewed-on: https://review.whamcloud.com/36137
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>