[Tests] Remove duplicate test (vllm-project#1500)

## Background ##
* When vllm-project#97 was merged, it accidentally created two test config files
which are identical
* Because the auto device is no longer tested,
`llama_7b_sparse_auto.yaml` is now identical to `llama_7b_sparse.yaml`

## Purpose ##
* Reduce testing runtime by removing duplicated test

Signed-off-by: Kyle Sayers <[email protected]>

Author: kylesayrs