Replaced file in ImageAdmin should reset subject_location

[viliammihalik]

Reproduction:

1. Upload image, for example, 500x500, subject location should be "250,250"
2. Go to the image and upload a smaller image via Advanced>File>Upload for example 100x100. Subject location will stay 250,250
3. Now if you try to upload another image with dimension let's say 150x150(must be smaller than subject location 250,250). Validation error will be thrown and you need to manually change subject location in input(you can't even change by dragging because the location circle can be outside of the image)

It is not straightforward what to do next when Subject location is outside of the image is raised and the user doesn't even use this property.

I propose to reset the subject location if the new image is uploaded via ImageAdmin.

[jrief]

Thanks for reporting

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[stale[bot]]

This will now be closed due to inactivity, but feel free to reopen it.