FIR: support adapted callable reference with vararg

compiler/testData/diagnostics/tests/callableReference/referenceAdaptationCompatibility.fir.kt

@@ -36,7 +36,7 @@ object Test3 {
 
         fun test() {
             val result = foo(::bar)
-            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int")!>result<!>
+            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.String")!>result<!>
         }
     }
 }