Revert "[Microsoft.Android.Sdk.ILLink] target net7.0 temporarily (#7803)"

This reverts commit 7ba7dd4.

Author: jonathanpeppers

src/Microsoft.Android.Sdk.ILLink/Microsoft.Android.Sdk.ILLink.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <Import Project="..\..\Configuration.props" />
   <PropertyGroup>
-    <TargetFramework>$(DotNetStableTargetFramework)</TargetFramework>
+    <TargetFramework>$(DotNetTargetFramework)</TargetFramework>
     <DefineConstants>ILLINK</DefineConstants>
     <AppendTargetFrameworkToOutputPath>false</AppendTargetFrameworkToOutputPath>
     <OutputPath>$(MicrosoftAndroidSdkOutDir)</OutputPath>