[benchmarks] enable TGI to use Hugging Face DLC

[annapendleton]

Validate and enable image use for ghcr.io/huggingface/text-generation-inference:1.4.2 to us-docker.pkg.dev/deeplearning-platform-release/gcr.io/huggingface-text-generation-inference-cu121.2-2.ubuntu2204.py310

We might also want to parameterize the image so that users can specify which image they want to benchmark, and offer the DLC image in a sample tfvars file for ease of deployment.

Conversation:
#816 (comment)