Remove prompt from image metadata when user chooses to hide the prompt

[BakkerHenk]

Currently when a user generates an image on-site, they can choose to hide the prompt.
When a user selects this option, the info button is hidden.

The image metadata however is still available. Using a simple metadata viewer, the prompt is still easily recovered.

I know removing the metadata will have consequenses like not being able to re-use the prompt even for the creator.
But currently hiding the prompt is pretty much useless. An alternative could be to explicitly warn the user that the prompt would still be easily recoverable.