chore(db, model): separate methods to drop a device vs its files (#10480)

Fixes #10469

---------

Signed-off-by: Simon Frei <freisim93@gmail.com>
Signed-off-by: Jakob Borg <jakob@kastelo.net>
Co-authored-by: Marcus B Spencer <marcus@marcusspencer.us>
Co-authored-by: Jakob Borg <jakob@kastelo.net>

lib/model/model.go

@@ -371,7 +371,7 @@ func (m *model) addAndStartFolderLockedWithIgnores(cfg config.FolderConfiguratio
 	for _, available := range devs {
 		if _, ok := expected[available]; !ok {
 			l.Debugln("dropping", folder, "state for", available)
-			_ = m.sdb.DropAllFiles(folder, available)
+			_ = m.sdb.DropFolderDevice(folder, available)
 		}
 	}