Remove legacy AssetGalleryField reference
Remove legacy AssetGalleryField reference

open-sausages/silverstripe-assets-gallery,silverstripe/silverstripe-asset-admin,open-sausages/silverstripe-asset-admin,open-sausages/silverstripe-asset-admin,open-sausages/silverstripe-assets-gallery,silverstripe/silverstripe-asset-admin