Crop should not be applied for images with external file scheme

Problem/Motivation

I noticed if the image is using external file scheme like some kind of CDN, then crop is not working and should not be applied, otherwise it causes Lock timeout issue when trying to save some entity.

Steps to reproduce

1. Use some contrib module to provide extrnal file scheme like cloudinary or flysystem
2. Choose an extranal scheme for your file/image field inside media type.
3. Create a new media entity and see that it takes forever and then you get database Lock timeout issue.

Proposed resolution

Let's limit file scheme to public and private only in focal_point_entity_update()