remove tensorpipe code which forgot to delete (#106301)
When analyzing the rpc code, I found redundant tensorpipe code, which was submitted synchronously with #40846, but was not deleted synchronously when the code was subsequently deleted.
The tensorpipe namespace is not useful in neither utils.h nor utils.cpp.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/106301
Approved by: https://github.com/ezyang, https://github.com/fduwjj
