[clang] [libc] [openmp] [Clang] Remove the old LLVM offloading driver entirely (PR #211924)

[Joseph Huber via cfe-commits]

jhuber6 wrote:

> Can this wait until after #206482

Do these conflict? Figured it'd be less work with less to update, but I'm not in a rush

https://github.com/llvm/llvm-project/pull/211924