[tests] Ignore unstable API levels when creating test projects

[pjcollins]

Context: 21751b5

Android API 32 is now "final", and is causing test failures on hosted
Azure Pipelines agents:

"/Users/runner/work/1/a/TestRelease/12-15_16.53.22/temp/XA4310apk/UnnamedProject.csproj" (Build;SignAndroidPackage target) (1:7) ->
(_CheckGoogleSdkRequirements target) -> 
  /Users/runner/Library/Android/dotnet/packs/Microsoft.Android.Sdk.Darwin/31.0.101-preview.12.144/targets/Microsoft.Android.Sdk.Tooling.targets(68,5): warning XA1008: The TargetFrameworkVersion (Android API level 31) is lower than the targetSdkVersion (32). Please increase the `$(TargetFrameworkVersion)` or decrease the `android:targetSdkVersion` in the `AndroidManifest.xml` so that the API levels match. [/Users/runner/work/1/a/TestRelease/12-15_16.53.22/temp/XA4310apk/UnnamedProject.csproj]

Fix this by ignoring invalid or unstable android versions when
determining which targetSdkVersion to use in the manifest files
of our test projects.

[pjcollins]

Looks like this is working:

[TESTLOG] Test AndroidAddKeepAlivesFalseFalseFalseFalse Starting
GetMaxInstalledPlatform: Parsing 15
GetMaxInstalledPlatform: Setting maxInstalled to 15
GetMaxInstalledPlatform: Parsing 23
GetMaxInstalledPlatform: Setting maxInstalled to 23
GetMaxInstalledPlatform: Parsing 24
GetMaxInstalledPlatform: Setting maxInstalled to 24
GetMaxInstalledPlatform: Parsing 25
GetMaxInstalledPlatform: Setting maxInstalled to 25
GetMaxInstalledPlatform: Parsing 22
GetMaxInstalledPlatform: Parsing 31
GetMaxInstalledPlatform: Setting maxInstalled to 31
GetMaxInstalledPlatform: Parsing 30
GetMaxInstalledPlatform: Parsing Sv2
GetMaxInstalledPlatform: Parsing 16
GetMaxInstalledPlatform: Parsing 29
GetMaxInstalledPlatform: Parsing 27
GetMaxInstalledPlatform: Parsing 18
GetMaxInstalledPlatform: Parsing 20
GetMaxInstalledPlatform: Parsing 21
GetMaxInstalledPlatform: Parsing 26
GetMaxInstalledPlatform: Parsing 19
GetMaxInstalledPlatform: Parsing 10
GetMaxInstalledPlatform: Parsing 17
GetMaxInstalledPlatform: Parsing 28
GetMaxInstalledPlatform: Parsing 32
msbuild /Users/runner/work/1/a/TestRelease/12-16_00.22.22/temp/AndroidAddKeepAlivesFalseFalseFalseFalse/UnnamedProject.csproj /t:Build,SignAndroidPackage /noconsolelogger "/flp1:LogFile=/Users/runner/work/1/a/TestRelease/12-16_00.22.22/temp/AndroidAddKeepAlivesFalseFalseFalseFalse/build.log;Encoding=UTF-8;Verbosity=diagnostic" -nodeReuse:false @"/Users/runner/work/1/a/TestRelease/12-16_00.22.22/temp/AndroidAddKeepAlivesFalseFalseFalseFalse/project.rsp"
Found Time Elapsed 00:00:23.2800000

[jonathanpeppers]

Looks good, I think we can just wait on MSBuild Legacy - macOS 1 to merge

Then hopefully this fixes our CI.

[pjcollins]

Looks like the GetMaxInstalledPlatform behavior in the latest run is working as expected if we want to go ahead and merge