Revert "FIR2IR: minimize scope processing in fake override generation"

This reverts commit 9934cfbb00.

See the tests added: Subclass may have private same-name method that
should not be a reason to avoid generating fake overrides

compiler/testData/codegen/box/traits/sameNameMethodFromInterface.kt

@@ -0,0 +1,9 @@
+interface A<T> {
+    fun foo(t: T): T = t
+}
+
+class B : A<String> {
+    private fun foo() {}
+}
+
+fun box(): String = B().foo("OK")