[jit] remove Dict iterationOrder and use insertion order (#36609)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/36609
This PR remove iterationOrder that backed by CompareKeys, we universally
use Dict inseration order default backed by c10::Dict to match the
python behaviors
Test Plan: Imported from OSS
Reviewed By: houseroad
Differential Revision: D21056963
Pulled By: wanchaol
fbshipit-source-id: 487961c2db2cdc27461b2fbd6df91faafc6920b5
