[IR][tests] Add tests for removal-of-overridden open callable case

compiler/testData/klibABI/removeOpenFunction/lib1/l1.kt

@@ -0,0 +1,7 @@
+open class C {
+    open fun foo(): String = "FAIL1"
+}
+
+interface I {
+    fun foo(): String = "FAIL2"
+}