click-service won't remove applications in user db (i.e. apps installed since Xenial)
Steps to reproduce:
- Flash Xenial image. Install any app from OpenStore.
- Flash Focal image.
- Try to remove the app with OpenStore, which will use DBus on Focal.
Expected result: the app is uninstalled.
Actual result: the app is still there.
This is because on Xenial, PackageKit plugin installs the package in user DB. However, on Focal click-service pretends that user DB doesn't exist and will just attempt to remove the package from the "all" DB. This creates confusion to the end user.