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/bound/genericValOnLHS.kt

@@ -7,6 +7,6 @@ class Host {
 
 fun box(): String {
     Generic(Host()).p::class
-    (Generic(Host()).p::t)()
-    return (Generic(Host()).p::v)()
+    (Generic(Host()).p::t).let { it() }
+    return (Generic(Host()).p::v).let { it() }
 }