[plugins] Android AAR builds are broken (Android property not found) #57846

Description

It seems like #46304 is still an issue for Android AARs and since recently all no-op android directories have been removed in flutter/plugins, this breaks any flutter build aar using any of those Flutter plugins.

Steps to Reproduce

1. Add url_launcher as a dependency:

url_launcher: 5.4.10

2. Run flutter build aar.
3. Experience the following build failure: https://stackoverflow.com/questions/59942331/android-property-not-found-error-while-building-flutter-aar

This happens because assembleAarDebug cannot be found for the url_launcher_web plugin that is automatically included when using flutter build aar.

This specific problem (for url_launcher) was caused by this PR from @cg021: flutter-team-archive/plugins#2776

FAILURE: Build failed with an exception.
* Where:
Initialization script '/opt/flutter/packages/flutter_tools/gradle/aar_init_script.gradle' line: 15
* What went wrong:
Android property not found.