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/controlStructures/kt2597.kt

@@ -5,6 +5,6 @@ fun box(): String {
             i++
         } else {
         }
-    }()
+    }.let { it() }
     return "OK"
 }