move reservation zfs tests to use ksh
confirmed issue by John Kennedy:
I can see several tests in BASH - for example: functional/reservation/reservation_001_pos.sh
is it added by mistake in BASH or some reason to use BASH for some tests?
They're a mistake. When I first sent the ZFS test suite for review,
I'd converted the scripts to bash, and during review I was told not to
do that. These examples must have not gotten converted back.