[Feature] option to use embedded thumbnail

[beneix]

I have searched the existing feature requests, both open and closed, to make sure this is not a duplicate request.

• Yes

The feature

In my setup, the thumbnail generation is one of the slower processes*. It would be useful to have an option to tell Immich to not generate a thumbnail if one exists embedded in the EXIF. Perhaps we could have a "Prefer embedded thumbnails" just as we have "Prefer embedded preview", or under the small thumbnail section below the "Progressive" toggle switch there could be a "Use embedded" toggle switch.

*) I was getting a lot of errors with failed requests to the remote ML server. After a lot of error tracing and experimentation, I concluded this was not to do with the remote ML server but with CPU exhaustion on the Immich server, which is a NAS with a not very powerful CPU. Setting the number of concurrent tasks for thumbnail generation to 1 seems to have got rid of those failures, but that means thumbnail generation is a real bottleneck when ingesting new images.

Platform

• Server
• Web
• Mobile