Report from gitlab-qa-mirror as master

This labels tests that run in master pipelines as ~"master::status" if they target either gitlab-qa or gitlab-qa-mirror.

Before this, reports from gitlab-qa-mirror were not obviously linked to master because they were labelled ~"gitlab-qa-mirror::failure" instead of ~"master::failure"

For example: https://gitlab.com/gitlab-org/quality/testcases/-/issues/419#note_316692579