[Mono.Android] delay JNINativeWrapper.get_runtime_types() (#7913)

Reviewing `dotnet-trace` output, I noticed in a `dotnet new maui` app
on a Pixel 5:

	6.38ms mono.android!Android.Runtime.JNINativeWrapper.CreateDelegate(System.Delegate)
	1.16ms mono.android!Android.Runtime.JNINativeWrapper.get_runtime_types()

We spend ~1ms looking up `AndroidEnvironment.UnhandledException()`
and `AndroidRuntimeInternal.WaitForBridgeProcessing()`.

However, in this app *all* calls go to the "fast path" via
`JNINativeWrapper.CreateBuiltInDelegate()`.  We don't *need* to look
up these methods in this app at all!

Delay the call to `get_runtime_types()` to only when it is needed via
the "slow path".  Will help us a small amount in .NET 8.

src/Mono.Android/Android.Runtime/JNINativeWrapper.cs

@@ -34,8 +34,6 @@ public static Delegate CreateDelegate (Delegate dlg)
 			if (dlg.Method == null)
 				throw new ArgumentException ();
 
-			get_runtime_types ();
-
 			var delegateType = dlg.GetType ();
 			var result = CreateBuiltInDelegate (dlg, delegateType);
 			if (result != null)
@@ -45,6 +43,8 @@ public static Delegate CreateDelegate (Delegate dlg)
 				RuntimeNativeMethods.monodroid_log (LogLevel.Debug, LogCategories.Assembly, $"Falling back to System.Reflection.Emit for delegate type '{delegateType}': {dlg.Method}");
 			}
 
+			get_runtime_types ();
+
 			var ret_type = dlg.Method.ReturnType;
 			var parameters = dlg.Method.GetParameters ();
 			var param_types = new Type [parameters.Length];