The ViewManager settings will be stored in the View Manager.json file in the calibre plugins folder.
BTW I *do not* recommend others do what you have done. Restoring a library in that way should be a last resort. You will *lose* information that is stored only in the database. You will also have a new library id, which as you have found means that any per library settings (which many plugins have) get lost. You will have to edit the .json files and very carefully replace the library guids if you want to retain the same settings you had previously or else recreate them.
I suspect much of your recovered space came from conversion settings that were persisted - something which can be far more safely removed using the bulk edit dialog from memory.