Remove CUDA from PyTorch/XLA build. (#9609)
This PR removes the CUDA specific build related source code. This is in
line with the CUDA deprecation that started on release 2.8.
**Key Changes:**
- (`.bazelrc`) Removed CUDA specific environment variables
- (`WORKSPACE`) Removed CUDA dependencies and CUDA specific OpenXLA
patches
- (`BUILD` files) Removed CUDA specific build dependencies
