Do not skip synthesized members when generating bridges

The condition here is obsolete since SAM adapters can no longer be overridden:
they are now extensions in another scope

 #KT-12708 Fixed

compiler/testData/codegen/box/dataClasses/copy/kt12708.kt

@@ -0,0 +1,13 @@
+fun box(): String {
+    val a: A = B(1)
+    a.copy(1)
+    a.component1()
+    return "OK"
+}
+
+interface A {
+    fun copy(x: Int): A
+    fun component1(): Any
+}
+
+data class B(val x: Int) : A