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/constructorFromTopLevelOneStringArg.kt

@@ -1,3 +1,3 @@
 class A(val result: String)
 
-fun box() = (::A)("OK").result
+fun box() = (::A).let { it("OK") }.result