[NI] Use compatibility mode for KT-41934

compiler/testData/diagnostics/tests/inference/regressions/kt41394.kt

@@ -1,12 +1,11 @@
 // FIR_IDENTICAL
 // !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_ANONYMOUS_PARAMETER
-// !LANGUAGE: +NewInference
+// !LANGUAGE: +InferenceCompatibility
 
-fun <T, VR : T> foo(x: T, fn: (VR?/*T?*/, T) -> Unit) {}
+fun <T, VR : T> foo(x: T, fn: (VR?, T) -> Unit) {}
 
 fun takeInt(x: Int) {}
 
 fun main(x: Int) {
     foo(x) { prev: Int?, new -> takeInt(new) } // `new` is `Int` in OI, `Int?` in NI
-    // It seems, `VR` has been fixed to `Int?` instead of `Int`
 }