Bugzilla

This bug is for defining and using Glean metrics to mirror Legacy Telemetry Environment fields in the `settings.intl` section. The fields and their needs are:

requestedLocales - **needs migration**
availableLocales - **needs migration**
appLocales - **needs migration**
systemLocales - **needs migration**
regionalPrefsLocales - **needs migration**
acceptLanguages - **needs migration**

" **needs migration**" means that the field must be either:
* removed (if you know that a field is unused or not useful, or can find an authority who can assert that), or 
* have a Glean metric defined for it in an appropriate `metrics.yaml` in an appropriate component in the tree and instrumentation code added in `TelemetryEnvironment.sys.mjs` so that it begins reporting data

Remember to update [the totals](https://searchfox.org/mozilla-central/rev/2a69486ab1df00b1ea8ecd14027e2cc6c0415ed0/toolkit/components/telemetry/app/TelemetryEnvironment.sys.mjs#84-86) for fields you migrate.

This bug is for defining and using Glean metrics to mirror Legacy Telemetry Environment fields in the `profile` section. The fields and their needs are:

creationDate - **needs migration**
resetDate - **needs migration**
furstUseDate - **needs migration** (though Glean reports its own date, this one is as old as the profile)

" **needs migration**" means that the field must be either:
* removed (if you know that a field is unused or not useful, or can find an authority who can assert that), or 
* have a Glean metric defined for it in an appropriate `metrics.yaml` in an appropriate component in the tree and instrumentation code added in `TelemetryEnvironment.sys.mjs` so that it begins reporting data

Remember to update [the totals](https://searchfox.org/mozilla-central/rev/2a69486ab1df00b1ea8ecd14027e2cc6c0415ed0/toolkit/components/telemetry/app/TelemetryEnvironment.sys.mjs#84-86) for fields you migrate.