Disable XLA builds (#80099)
As they are constantly failing to download llvm release from https://storage.googleapis.com:
```
Error in download_and_extract: java.io.IOException: Error downloading [https://storage.googleapis.com/mirror.tensorflow.org/github.com/llvm/llvm-project/archive/9c6a2f29660b886044a267bb4de662cd801079bc.tar.gz, https://github.com/llvm/llvm-project/archive/9c6a2f29660b886044a267bb4de662cd801079bc.tar.gz] to /home/jenkins/.cache/bazel/_bazel_jenkins/b463291cb8b07b4bfde1e3a43733cd1a/external/llvm-raw/temp10926951092717297163/9c6a2f29660b886044a267bb4de662cd801079bc.tar.gz: Read timed out
Loading: 0 packages loaded
```
cc: @JackCaoG
Pull Request resolved: https://github.com/pytorch/pytorch/pull/80099
Approved by: https://github.com/janeyx99
