Cleanup thread pool tasks creation.
Cleanup thread pool tasks creation.

Removes unused vector when adding new ForAllClosure tasks to the thread pool.

Change-Id: Ie0c8067bc5cbfac45db04a6242bc98f89c3efc8d

treadstoneproject/artinst,treadstoneproject/artinst,treadstoneproject/artinst,treadstoneproject/artinst,treadstoneproject/artinst