WIP: Add vLLM support to ChatQnA + DocSum Helm charts

[eero-t]

Description

Add vLLM support to ChatQnA + DocSum Helm app charts.

Similarly to how it's already done in Agent component, these have now tgi.enabled and vllm.enabled flags for selecting which LLM will be used.

Notes:

• Using vLLM with DocSum app requires building llm-docsum-vllm wrapper image from GenAIComps repo, as that image is currently missing from DockerHub
• ChatQnA vLLM version will still use HF TEI for embedding & reranking

Issues

Fixes #608 partially.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds new functionality)

New dependencies

• opea/llm-docsum-vllm:latest image is currently missing from CI & DockerHub registries: https://github.com/opea-project/GenAIComps/tree/main/comps/llms/summarization/vllm/langchain/

Tests

Manual testing on top of "main" HEAD / v1.1 images.

[eero-t]

Setting as draft. I have tested that DocSum with Gaudi vLLM works, and that ChatQnA Helm chart can be installed, but due to v1.1 image pulls currently taking so long in my test node, I haven't been able test ChatQnA with Gaudi vLLM properly yet.

vLLM CPU version testing would also be needed before merging this (I'm hoping somebody else here could check at least DocSum with CPU vLLM).

[eero-t]

CI issues:

• LLM-uservice: openai.NotFoundError: Error code: 404 - {'object': 'error', 'message': 'The model meta-llama/Meta-Llama-3-8B-Instruct does not exist.', 'type': 'NotFoundError', 'param': None, 'code': 404}
  • Bug already in the CI/repo, pre-existing Helm chart refers to model not present in CI => I can fix it
• DocSum: 100.83.111.229:5000/opea/llm-docsum-vllm:latest: not found
  • Bug in OPEA image creation, that image is missing from DockerHub & CI => somebody else needs to fix that

[eero-t]

This overlaps partly with #403.

[eero-t]

Added HPA support for ChatQnA / vLLM.