Mistakenly alerted about non-expiring metrics.

Today the expiry mails complained about several metrics in engine-gecko:

- geckoview.build_id on 2021-02-01
- geckoview.version on 2021-02-01
- gfx.adapter.primary.description on 2021-02-01
- gfx.adapter.primary.device_id on 2021-02-01
- gfx.adapter.primary.driver_date on 2021-02-01
- gfx.adapter.primary.driver_files on 2021-02-01
- gfx.adapter.primary.driver_vendor on 2021-02-01
- gfx.adapter.primary.driver_version on 2021-02-01
- gfx.adapter.primary.ram on 2021-02-01
- gfx.adapter.primary.subsystem_id on 2021-02-01
- gfx.adapter.primary.vendor_id on 2021-02-01
- gfx.display.count on 2021-02-01
- gfx.display.primary_height on 2021-02-01
- gfx.display.primary_width on 2021-02-01
- gfx.status.compositor on 2021-02-01
- gfx.status.headless on 2021-02-01

These were all switched to never expire in bug 1687219, that landed 20 days ago.

• Current metrics.yaml in Gecko

Doesn't seem right that we send an email about that, but I'm not sure where to look at the moment.
Is the logic wrong and it skips never expiry if if already found an expiry?

Start by tracing the expiry-mail logic against the metrics listed in toolkit/components/telemetry/geckoview/streaming/metrics.yaml, focusing on the never-expire settings referenced in the issue. Done means metrics marked never no longer appear in expiry alerts, including the linked Gecko metrics.