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

This fixes KT-43117

plugins/kapt3/kapt3-compiler/testData/converter/invalidFieldName.txt

@@ -1,5 +1,3 @@
-import java.lang.System;
-
 @Anno(color = Color.InvalidFieldName)
 @java.lang.annotation.Retention(value = java.lang.annotation.RetentionPolicy.RUNTIME)
 @kotlin.Metadata()
@@ -11,8 +9,6 @@ public abstract @interface Anno {
 ////////////////////
 
 
-import java.lang.System;
-
 @kotlin.Metadata()
 public enum Color {
     /*public static final*/ BLACK /* = new Color() */;