Description of problem:

In RHDH-local, add support vertexai provider support to work with Gemini model.

Version-Release number of selected component (if applicable):

v1.9

How reproducible:

Always

Steps to Reproduce:

1. Use Gemini model with Vllm provider

Actual results:

Gemini model is not supported and lightspeed isn't working

Expected results:

Lightspeed should be working with Gemini model

Additional info:

Slack thread - https://redhat-internal.slack.com/archives/C07N7CR4FFH/p1764084340028729