JVM IR: Avoid direct invokes in callable reference tests

Due to the direct invoke optimization, most callable reference tests
were not generating callable references/lambdas.

compiler/testData/codegen/box/functions/kt2481.kt

@@ -9,6 +9,6 @@ public class B(): A(){
     public override fun method() : String {
         return ({
           super.method()
-        })()
+        }).let { it() }
     }
 }