Enable Kroki to support more Markdown diagram formats
As of gitlab-org/gitlab!44851 (merged), GitLab will support Kroki (https://docs.gitlab.com/ee/administration/integration/kroki.html) to render more diagram formats.
This can replace the PlantUML server that was added in https://gitlab.com/gitlab-com/gl-infra/infrastructure/-/issues/2163.
@jarv Do you think this is a good idea?