I know that it's feature, but I think You must give user a choice. Notifications were convenient functionality, with them I can see what really happening during the installation process and see when the installation actually finishes.
Now it's very uncomfortable, specially when a user tries to install update of the application. I double-clicking on APK, then what? I need to wait about 10-15 seconds, right? But what if apk don't installed during this time period? I run application and think it's updated already, but actually it's not.
I think you see the problem now. Notifications were user-friendly feature. At least notification about process starts and finish.