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/UnitAsGenericArgument.java

@@ -1,4 +1,4 @@
-public final class C implements kotlin.jvm.internal.KObject, Base<kotlin.Unit> {
+public final class C implements Base<kotlin.Unit> {
     public void foo(@org.jetbrains.annotations.NotNull kotlin.Unit t) { /* compiled code */ }
 
     public C() { /* compiled code */ }