FIR checker: fix position strategy for UNRESOLVED_LABEL

compiler/testData/diagnostics/tests/regressions/UnavaliableQualifiedThis.fir.kt

@@ -4,10 +4,10 @@ interface Iterator<out T> {
 
  fun <R> map(transform: (element: T) -> R) : Iterator<R> =
     object : Iterator<R> {
-      override fun next() : R = transform(<!UNRESOLVED_LABEL!>this@map<!>.<!UNRESOLVED_REFERENCE!>next<!>())
+      override fun next() : R = transform(this<!UNRESOLVED_LABEL!>@map<!>.<!UNRESOLVED_REFERENCE!>next<!>())
 
       override val hasNext : Boolean
         // There's no 'this' associated with the map() function, only this of the Iterator class
-        get() = <!UNRESOLVED_LABEL!>this@map<!>.<!UNRESOLVED_REFERENCE!>hasNext<!>
+        get() = this<!UNRESOLVED_LABEL!>@map<!>.<!UNRESOLVED_REFERENCE!>hasNext<!>
     }
-}
+}