Duplicating a variation copies the creation time

Describe your bug or feature request.

When you duplicate a variation the creation time from the original is copied to the new variation. This interferes with the usefulness of the creation time field on variations. It should be set to the time the duplicate variation was created.

If a bug, provide steps to reproduce it from a clean install.

Edit the form display for the default variation type. Ensure created field is enabled so you can see the creation time.
Create a product with a variation. Go to the variations tab on the product and duplicate a variation. Check the creation time of the duplicate.

While this isn't displayed anywhere on variations it is useful for business logic that uses things such as the Drupal API to set prices, update listings, etc which this potentially interferes with.