[Data masking] Warning for field in migrate mode is overagressive

[jerelmiller]

To aid in migrating to data masking, we've included a warning when a would-be masked field is accessed (#11919). This however is triggering too often because we have internal client code (such as cache.identify) which trigger the getter on those fields, such as when a spread operator is used. This results in a noisy console even when the end user isn't actually accessing those fields.