Delete kotlin.jvm.internal.KObject

It was supposed to be used in reflection but the benefits do not outweigh the
cost of KT-6951

 #KT-3223 Fixed
 #KT-6951 Fixed

compiler/testData/asJava/lightClasses/nullabilityAnnotations/ClassWithConstructor.java

@@ -1,3 +1,3 @@
-public final class ClassWithConstructor implements kotlin.jvm.internal.KObject {
+public final class ClassWithConstructor {
     public ClassWithConstructor(@org.jetbrains.annotations.Nullable java.lang.String nullable, @org.jetbrains.annotations.NotNull java.lang.String notNull) { /* compiled code */ }
 }