[jit] delete netdef converter (#33807)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/33807
afaik this is unused, so removing it from the source tree. RIP :(
Test Plan: Imported from OSS
Differential Revision: D20122118
Pulled By: suo
fbshipit-source-id: cb45943f5b9f969482301a2f9fe540326dbc78f2
