fix tests that could have racy script module instantiation (#34792)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/34792
it is not thread safe to initiate script module in multiple threads.
for both test_remote_script_module and test_torchscript_functions_not_supported, it is possible that client thread is initiating MyScriptModule while server thread is initiating it as well in the same rank process.
removing MyScriptModule instatiation in client thread, it is not needed actually.
ghstack-source-id: 100266609
Test Plan: unit tests
Differential Revision: D20463234
fbshipit-source-id: 6ff70ad90fa50b0b44c78df2495b4bcaabb4487b
