[Static Runtime] Remove wrappers for aten::cat (#62067)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/62067
The wrapper for aten::cat is no longer needed after the variadic cat change in D29565344 (https://github.com/pytorch/pytorch/commit/ae58a4c45de4cb16949934b33a93e79d3aca4350) .
Also added a simple test to test dynamic shapes, i.e., input tensors in args2 are larger than in args1.
Reviewed By: navahgar, mikeiovine
Differential Revision: D29864600
fbshipit-source-id: 44a712c2e776815c09e0bf5631412149b81274b2
