Support for Spark DL notebooks on databricks/dataproc

[rishic3]

Support for running DL Inference notebooks on CSP environments.

Notebook changes:

• Refactored Triton sections to use PyTriton, a Python API for the Triton inference server which avoids Docker. Once this PR is merged, Triton sections no longer need to be skipped in the CI pipeline @YanxuanLiu .
• Updated notebooks with Databricks/Dataproc specific Spark configurations and file paths.
• Updated Torch notebooks with best practices for ahead-of-time TensorRT compilation.

Other changes:

• Added instructions and init scripts for Databricks/Dataproc.
• Cleaned up README, removing instructions to start Jupyter with PySpark (we need a cell to attach to standalone for CI/CD anyway, so hoping to reduce confusion for user).

Notebook outputs are saved from running locally, but all notebooks were tested on Databricks/Dataproc.