[FIR] Prevent duplicate direct overridden-s from substitution overrides

This change prevents going up the scopes once we find a
substitution override. Whatever we'd find by going further is not
going to be a direct overridden anymore, so it would lead to incorrect
results when collecting direct overridden-s. Without this change, we get
error modules in FT intellij.

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

@@ -0,0 +1,14 @@
+// FIR_IDENTICAL
+
+interface Foo<T> {
+    fun foo() {}
+    fun foo(param: Int = 1) {}
+}
+
+open class Test<K> : Foo<K> {
+    override fun foo() {}
+}
+
+open class Rest<R> : Test<R>(), Foo<R>
+
+class Baz : Rest<Int>() {}