The Linux_android_legacy suite of tests in flutter/packages are intended to make sure our plugins work on old versions of Android that are within our support window; see #130010 for background.

Ideally, we would run them on the oldest API version we support, so that we have tests at the oldest version and at ~the newest version, giving us assurance that the endpoints work. Until recently, the legacy tests were running 22 (not 21, because we didn't have a workable 21 emulator), giving us almost complete coverage. As of flutter/packages#9416 however, we are running on 31 instead, because all of the low-API-version options on https://chromium.googlesource.com/chromium/src.git/+/HEAD/tools/android/avd/proto are x86, and Flutter just dropped x86 support for Android.

Filing this to track investigating (if the team-android thinks it's a worthwhile investment of time) adding a new config there that uses a x64 emulator and an old API version, to restore older legacy runtime testing in CI.