Optimize more redundant kotlin/jvm/internal/Refs

The number of initializations of the `value` field before the live range
begins does not really matter so long as we insert a write of a default
value to the local if there were none.

compiler/testData/codegen/bytecodeText/localInitializationLVT/boxingVar.kt

@@ -6,5 +6,5 @@ fun test(): java.lang.Integer {
     return c
 }
 
-// 1 ASTORE 0
-// 1 LOCALVARIABLE c Lkotlin/jvm/internal/Ref\$ObjectRef; L1 L.* 0
+// 2 ASTORE 0
+// 1 LOCALVARIABLE c Ljava/lang/Object;