Only build for ARM by default?

### What is the problem or limitation you are having?

I discovered recently that the Android emulator was [updated](https://android-developers.googleblog.com/2020/03/run-arm-apps-on-android-emulator.html) several years back to support running ARM binaries on x86 Android.

### Describe the solution you'd like

So, with that in mind, is there still value in building for x86-64, by default? Or, said another way, is there value in continuing to target x86-64 as well as arm64 beyond support for the Android emulator on x86?

If not, should x86-64 be removed from default builds?

### Describe alternatives you've considered

Status quo.

### Additional context

I'm assuming that x86-64 builds are only done for the Android emulator; obviously, if there are other reasons, this point is moot.

No file or test is named. Review the Android Gradle template's architecture and build configuration first, then check which emulator or other targets require x86-64; done means reaching a documented decision on whether x86-64 should remain in default builds.

Written by the indexing model from the issue text.