KAPT: Skip importing java.lang.System in the stubs

This fixes KT-43117

plugins/kapt3/kapt3-compiler/testData/kotlinRunner/NestedClasses.it.txt

@@ -7,8 +7,6 @@ public final class NonExistentClass {
 
 package test;
 
-import java.lang.System;
-
 @java.lang.annotation.Retention(value = java.lang.annotation.RetentionPolicy.RUNTIME)
 @kotlin.Metadata()
 public abstract @interface MyAnnotation {
@@ -18,8 +16,6 @@ public abstract @interface MyAnnotation {
 
 package test;
 
-import java.lang.System;
-
 @kotlin.Metadata()
 public final class Simple {
     @org.jetbrains.annotations.NotNull()