FIR: use default getter in serializer if fir contains none

since we generate the default getter in this case in
Fir2IrDeclarationStorage.createIrProperty, so the serialized metadata
should follow the same behavior.
#KT-57373 fixed

compiler/testData/codegen/box/delegation/delegationDifferentModule2.kt

@@ -0,0 +1,24 @@
+// MODULE: lib
+// FILE: lib.kt
+
+interface I {
+    val bar: Int
+}
+
+class Impl : I {
+    override val bar: Int = 42
+}
+
+class D1(foo: I) : I by foo
+
+// MODULE: main(lib)
+// FILE: main.kt
+
+class D2(foo: I) : I by foo
+
+fun box() : String {
+    val c = Impl()
+    if (D1(c).bar != 42) return "FAIL 1"
+    if (D2(c).bar != 42) return "FAIL 2"
+    return "OK"
+}