fix: init 768 dimension in database for gaianet

[L-jasmine]

Relates to:

Risks

Low

Background

What does this PR do?

Initialize the resources required for gaianet embedding like any other embedding model

What kind of change is this?

Bug fixes (non-breaking change which fixes an issue)

Documentation changes needed?

If a docs change is needed: I have updated the documentation accordingly.

Testing

...

GAIANET_MODEL=llama3b
GAIANET_SERVER_URL=https://llama3b.gaia.domains/v1
GAIANET_EMBEDDING_MODEL=nomic-embed
USE_GAIANET_EMBEDDING=TRUE

...

And chat with a agent.

Where should a reviewer start?

Detailed testing steps

None, automated tests are fine.