Tab opened and FxA received_tab metric labels are _other_ in the table

[daoshengmu]

Configuration

Firefox Reality version:
Firefox Reality build ID: v.10

Hardware:
All the devices

Steps to Reproduce

1. Visit https://sql.telemetry.mozilla.org/queries/70315/source

Current Behavior

We are using TabSource.name() and DeviceType.name(), it will return uppercase letters. According to Glean doc [1], it is not allowed.

[1] https://mozilla.github.io/glean/book/user/metrics/labeled_counters.html#limits

Expected Behavior

The fields in our metric table should have keys and values instead of a _other_.

Possible Solution

We should toLowerCase() it and give unit tests to prevent this kind of issue be happened again.

[daoshengmu]

Actually, our GleanMetricsServiceTest can help us catch this bug if we follow the new version of Glean. I can see running failures once doing a new update.