Revert D26179083: [TensorExpr] Introduce ExternalCall nodes to TE IR.
Test Plan: revert-hammer
Differential Revision:
D26179083 (https://github.com/pytorch/pytorch/commit/f4fc3e3920c75ba978765dcaded39a606eb7992a)
Original commit changeset: 9e44de098ae9
fbshipit-source-id: d15684e04c65c395b4102d4f98a4488482822d1b
