Fenix Use of Glean

Glean is the telemetry library that Fenix uses, which I think we don't want to add to the final apk.

There two ways to handle this

1. Create a TBB project for glean and include it as a compile time dependency in android-components. Then we just don't include the aar in the final project, which disables the feature.
2. Patch the Fenix project to not use glean

I'm not that keen on (1) since we have to pull in and configure rust. (2) also seems a bit of a pain because the android-components is going through heavy development would require redoing the patches each time.

I have pref for (2). Thoughts?

Remark from components/browser/engine-gecko-nightly/build.gradle

    // We only compile against Glean. It's up to the app to add those dependencies
    // if it wants to collect GeckoView telemetry through the Glean SDK.

Project: https://github.com/mozilla/glean