[FIR] Ensure K2 reports redundant diagnostics for default values

compiler/testData/diagnostics/tests/override/MultipleDefaultsAndSubstitutionOverrides.kt

@@ -0,0 +1,15 @@
+interface A<T> {
+    fun foo(x: Int = 42): Int
+}
+
+open class B<K> {
+    fun foo(x: Int = 239) = x
+}
+
+interface C<E> {
+    fun foo(x: Int): Int
+}
+
+open <!MULTIPLE_DEFAULTS_INHERITED_FROM_SUPERTYPES_WHEN_NO_EXPLICIT_OVERRIDE!>class Z<!><R> : A<R>, B<R>(), C<R>
+
+class N<W> : Z<W>()