K2 opt-in: drop redundant recursive check for overridables

compiler/testData/diagnostics/testsWithStdLib/experimental/overridableCheck.fir.kt

@@ -0,0 +1,22 @@
+@RequiresOptIn
+@Target(AnnotationTarget.TYPEALIAS, AnnotationTarget.FUNCTION)
+annotation class Marker
+
+class Wrapper<T>
+
+@Marker
+typealias TA<T> = Wrapper<T>
+
+open class Base<T> {
+    @Marker
+    open fun foo(): T? = null
+
+    open fun bar(): <!OPT_IN_USAGE_ERROR!>TA<T><!>? = null
+}
+
+class Derived : Base<String>()
+
+fun test(d: Derived) {
+    d.<!OPT_IN_USAGE_ERROR!>foo<!>()
+    d.<!OPT_IN_USAGE_ERROR!>bar<!>()
+}