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/callableReference/function/local/simple.kt

@@ -1,4 +1,4 @@
 fun box(): String {
     fun foo() = "OK"
-    return (::foo)()
+    return (::foo).let { it() }
 }