[FE 1.0] Update DUPLICATE_LABEL_IN_WHEN testdata

New diagnostics started to report because in 1.6 we assume that
  `1` is typed const of type Int instead of literal const

compiler/testData/diagnostics/tests/when/When.kt

@@ -43,7 +43,7 @@ fun test() {
     <!INCOMPATIBLE_TYPES!>s<!> -> 1
     <!DUPLICATE_LABEL_IN_WHEN, INCOMPATIBLE_TYPES!>""<!> -> 1
     x -> 1
-    1 -> 1
+    <!DUPLICATE_LABEL_IN_WHEN!>1<!> -> 1
   }
 
   val z = 1