Fix UTF-8 JNI lookup tests for Android (#1398)

On Android, JNI FindClass throws ClassNotFoundException (not generic
JavaException) and GetMethodID throws NoSuchMethodError. The existing
string-based tests in JniTypeTest.cs already use #if __ANDROID__
conditionals for the same reason — apply the same pattern to the new
UTF-8 overload tests.

Fixes dotnet/android#10993

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: simonrozsival

tests/Java.Interop-Tests/Java.Interop/JniTypeUtf8Test.cs

@@ -46,7 +46,11 @@ public void FindClass_Utf8_ReturnsValidReference ()
 		[Test]
 		public void FindClass_Utf8_ThrowsOnNotFound ()
 		{
+#if __ANDROID__
+			Assert.Throws<Java.Lang.ClassNotFoundException> (() => JniEnvironment.Types.FindClass ("does/not/Exist"u8));
+#else   // __ANDROID__
 			Assert.Throws<JavaException> (() => JniEnvironment.Types.FindClass ("does/not/Exist"u8));
+#endif  // __ANDROID__
 		}
 
 		[Test]
@@ -172,7 +176,11 @@ public void Dispose_Exceptions_Utf8 ()
 		public void InvalidSignature_Utf8_ThrowsJniException ()
 		{
 			using (var Object_class = new JniType ("java/lang/Object"u8)) {
+#if __ANDROID__
+				Assert.Throws<Java.Lang.NoSuchMethodError> (() => Object_class.GetInstanceMethod ("bogus"u8, "(Z)V"u8));
+#else   // __ANDROID__
 				Assert.Throws<JavaException> (() => Object_class.GetInstanceMethod ("bogus"u8, "(Z)V"u8));
+#endif  // __ANDROID__
 			}
 		}
 	}