If I select to download the upgrade package only, it should not include the following files:
Why? Because these two files are used regardless of the style settings of your forum. So even though I dont use the default Xenforo style, I still must continually overwrite these two files. Technically, since these two files are used regardless of style choices... they shouldn't even be in this folder. They should probably be in the root styles folder.
The files are taken from wherever you have set up as your imagePath style property. It defaults to styles/default but if you're not using the default style then you should change this and serve your image files from a different path.
That's why, as Mike corrected me, the ogLogoPath setting is different to the imagePath. If you want your og logo to not be overwritten, just change the property and move your og logo there. That said, I have known sites to use different open graph logos for different styles so that use case isn't entirely invalid.