Add maintainer projects to hustewart.yml

Why

https://gitlab.com/gitlab-org/configure/k8s-agent-qa does not currently have a maintainer. Previously, members of Configure team who have now moved to different teams were tending to this project.

This belongs to Environments so we need a maintainer from that group.

I've been helping out with this more since the team changes and would like to take a maintainer role in this project.

What

• add k8s-agent-qa with maintainer role to my projects section