fix size accounting for encrypted/compressed objects (#9690)

size calculation in crawler was using the real size
of the object instead of its actual size i.e either
a decrypted or uncompressed size.

this is needed to make sure all other accounting
such as bucket quota and mcs UI to display the
correct values.

cmd/object-api-utils_test.go

@@ -521,7 +521,7 @@ func TestGetActualSize(t *testing.T) {
 		},
 	}
 	for i, test := range testCases {
-		got := test.objInfo.GetActualSize()
+		got, _ := test.objInfo.GetActualSize()
 		if got != test.result {
 			t.Errorf("Test %d - expected %d but received %d",
 				i+1, test.result, got)