Remove references for the 'task_state' property

Complementing the patch 45671, this patch removes all the references of
'task_state' in the current code. The 'task_state' property was replaced
by two new properties 'power_state' and 'provision_state' on a previous
patch.

Change-Id: I1f6bbcdfcebb0e2551855fbd17e1241b9c84b741