[NI] Add test for obsolete issue

It was fixed after c6712ff861

 #KT-25182 Obsolete

compiler/testData/diagnostics/tests/generics/nullability/kt25182.kt

@@ -0,0 +1,14 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+abstract class Expr<T>
+
+class Sum<K>(val e: Expr<K>) : Expr<K?>()
+
+private fun <V> times(e: Expr<V>, element: V): Expr<V> = TODO()
+
+private fun <S> foo(e: Expr<S>) {}
+
+fun test(intExpression: Expr<Int>) {
+    foo(Sum(times(intExpression, 42)))
+}