Add screenshots to failure issues

What does this MR do and why?

Adds screenshots to automated failure issues to make triaging QA failures more streamlined.

See: https://gitlab.com/gitlab-org/quality/team-tasks/-/issues/726

We are already updating the screenshot path in the xml report from the path inside the docker container to the actual artifact path so we extend that here to also include the json report. Then for adding the screenshots to the failure issue description, we must upload the file to the project first, then link the relative url with markdown.

Screenshots or screen recordings

Example from testing this in GDK:

MR acceptance checklist

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