Fix GLQL visualization in Duo chat UI

Problem to solve

Given a GLQL query, Duo should be able to render the result in the chat UI. The problem to solve is that GitLab flavoured markdown (GFM) is broken in Duo UI chat.

The renderGFM function can't render mermaid charts or GLQL in Duo UI (@gitlab/duo-ui) because LLM messages are streamed and Duo UI calls renderGFM before a message has finished streaming and with incomplete code, causing errors.

Example

Duo responds with a partial code block as it's streaming and GFM throws and error for the invalid GLQL.

display: table
fields: title, type, 

Proposal

Update the behaviour so that GFM only renders markdown in Duo messages that has finished streaming.

Related

POC work item with discussions https://gitlab.com/gitlab-org/gitlab/-/work_items/570284+

Implementation plan

Work with the AI teams on a more thorough solution that solves GFM rendering in @gitlab/duo-ui.