[tests] bump to API 30 emulator

[jonathanpeppers]

Context: https://dl-ssl.google.com/android/repository/sys-img/google_apis/sys-img2-1.xml

This will use the API 30 emulator for all tests.

[jonathanpeppers]

It says that Mono.Android-Tests failed, it seems like they didn't even start:

RunInstrumentationTests
    Executing: /Users/runner/Library/Android/sdk/platform-tools/adb -s emulator-5570  shell am instrument  -e "loglevel Verbose" -w "Mono.Android_Tests/xamarin.android.runtimetests.TestInstrumentation"
    Warnings
        /Users/runner/runners/2.171.1/work/1/s/build-tools/scripts/TestApks.targets(240,5):   Process '/Users/runner/Library/Android/sdk/platform-tools/adb -s emulator-5570  shell am instrument  -e "loglevel Verbose" -w "Mono.Android_Tests/xamarin.android.runtimetests.TestInstrumentation"' failed to exit within the timeout of 1800000ms, killing the process [/Users/runner/runners/2.171.1/work/1/s/src/Mono.Android/Test/Mono.Android-Tests.csproj]
    Errors
        /Users/runner/runners/2.171.1/work/1/s/build-tools/scripts/TestApks.targets(240,5):   Command /Users/runner/Library/Android/sdk/platform-tools/adb -s emulator-5570  shell am instrument  -e "loglevel Verbose" -w "Mono.Android_Tests/xamarin.android.runtimetests.TestInstrumentation" failed with exit code -1 [/Users/runner/runners/2.171.1/work/1/s/src/Mono.Android/Test/Mono.Android-Tests.csproj]
        /Users/runner/runners/2.171.1/work/1/s/build-tools/scripts/TestApks.targets(240,5): Could not find NUnit2 results file after running component `Mono.Android_Tests/xamarin.android.runtimetests.TestInstrumentation`: no `nunit2-results-path` bundle value found in command output! [/Users/runner/runners/2.171.1/work/1/s/src/Mono.Android/Test/Mono.Android-Tests.csproj]
    OutputItems
        _FailedComponent = Mono.Android_Tests/xamarin.android.runtimetests.TestInstrumentation
    Build continuing because "ContinueOnError" on the task "RunInstrumentationTests" is set to "ErrorAndContinue".

[jonathanpeppers]

I'll let dean take this over in #5257