LU-7991 osd-zfs: remove obsolete quota code

LU-7991 osd-zfs: remove obsolete quota code

Directly use ZFS backend quota accounting objects,
no need be mapped from Lustre own account objects.
Related obsolete logic is removed totally.

Signed-off-by: Fan Yong <fan.yong@intel.com>
Change-Id: I2c6aeb1ccac52348d8d163017f73ef0fd9133551
Reviewed-on: https://review.whamcloud.com/27661
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Nathaniel Clark <nathaniel.l.clark@intel.com>
Reviewed-by: Niu Yawei <yawei.niu@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>