[Mono.Android] fix "replaceable" objects in ManagedValueManager (#10107)

Context: d3d3584
Context: dotnet/java-interop@d3d3a1b

The following test was failing on NativeAOT as well as whenever we'd
use `ManagedValueManager`:

	[Test]
	public void JnienvCreateInstance_RegistersMultipleInstances ()
	{
	  using (var adapter = new CreateInstance_OverrideAbsListView_Adapter (Application.Context)) {

	    var intermediate  = CreateInstance_OverrideAbsListView_Adapter.Intermediate;
	    var registered    = Java.Lang.Object.GetObject<CreateInstance_OverrideAbsListView_Adapter>(adapter.Handle, JniHandleOwnership.DoNotTransfer);

	    Assert.AreNotSame (adapter, intermediate); // Passes
	    Assert.AreSame (adapter, registered);      // Fails!
	  }
	}

With the assertion:

	Expected: same as <com.xamarin.android.runtimetests.CreateInstance_OverrideAbsListView_Adapter{cbd0e5a V.ED.VC.. ......I. 0,0-0,0}>
	But was:  <com.xamarin.android.runtimetests.CreateInstance_OverrideAbsListView_Adapter{cbd0e5a V.ED.VC.. ......I. 0,0-0,0}>

The second assertion fails because `registered` is the same instance
as `intermediate`.  In this example, this is a code path where
`intermediate` should be "replaced" with `adapter`.

After lots of debugging, I found the problem are these lines in the
`ManagedValueManager.AddPeer()` method:

	var o = PeekPeer (value.PeerReference);
	if (o != null)
	    return;

If we `PeekPeer()` in the middle of `AddPeer()` and a type is
"replaceable", it would find an instance and not replace it! I did not
find equivalent code in `AndroidValueManager.AddPeer()`, which is what
is used in Mono & production today.

This was also addressed in Java.Interop's `ManagedValueManager` by
dotnet/java-interop@d3d3a1bf.

This also solves a test failure in `Java.Interop-Tests`:

	Mono.Android.NET_Tests, Java.InteropTests.InvokeVirtualFromConstructorTests.CreateManagedInstanceFirst_WithNewObject / Release
	
	Error message
	    Expected t and registered to be the same instance; t=20dfddd, registered=325d330
	    Expected: same as net.dot.jni.test.CallVirtualFromConstructorDerived@564f0f8
	    But was:  net.dot.jni.test.CallVirtualFromConstructorDerived@564f0f8
	Stack trace
	    at Java.InteropTests.InvokeVirtualFromConstructorTests.CreateManagedInstanceFirst_WithNewObject()
	    at System.RuntimeMethodHandle.InvokeMethod(ObjectHandleOnStack, Void**, ObjectHandleOnStack, BOOL, ObjectHandleOnStack)
	    at System.RuntimeMethodHandle.InvokeMethod(ObjectHandleOnStack, Void**, ObjectHandleOnStack, BOOL, ObjectHandleOnStack)
	    at System.RuntimeMethodHandle.InvokeMethod(Object, Void**, Signature, Boolean)
	    at System.Reflection.MethodBaseInvoker.InterpretedInvoke_Method(Object obj, IntPtr* args)
	    at System.Reflection.MethodBaseInvoker.InvokeWithNoArgs(Object, BindingFlags)

Author: jonathanpeppers

src/Mono.Android/Microsoft.Android.Runtime/ManagedValueManager.cs

@@ -67,9 +67,6 @@ public override void AddPeer (IJavaPeerable value)
 		var r = value.PeerReference;
 		if (!r.IsValid)
 			throw new ObjectDisposedException (value.GetType ().FullName);
-		var o = PeekPeer (value.PeerReference);
-		if (o != null)
-			return;
 
 		if (r.Type != JniObjectReferenceType.Global) {
 			value.SetPeerReference (r.NewGlobalRef ());

tests/Mono.Android-Tests/Mono.Android-Tests/Java.Lang/ObjectTest.cs

@@ -66,8 +66,6 @@ static MethodInfo MakeGenericMethod (MethodInfo method, Type type) =>
 		}
 
 		[Test]
-		[Category ("CoreCLRIgnore")] //TODO: https://github.com/dotnet/android/issues/10069
-		[Category ("NativeAOTIgnore")] //TODO: https://github.com/dotnet/android/issues/10079
 		public void JnienvCreateInstance_RegistersMultipleInstances ()
 		{
 			using (var adapter = new CreateInstance_OverrideAbsListView_Adapter (Application.Context)) {