[dynamo] Reserve the tensorrt backend name for torch-tensorrt (#94632)
In PR #93822 the `fx2trt` backend was removed which registered the `tensorrt` backend names to point to `fx2trt` / `torch_tensorrt` and move the name to `onnxrt`. We want to reserve the name `tensorrt` for `torch_tensorrt` to prevent any confusion but due to code-freeze we cannot complete the integration and set up testing for the next release. So we propose leaving out the `tensorrt` name until we can set up the backend and testing for it.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/94632
Approved by: https://github.com/frank-wei
