test: drop PackageKit state on Arch Linux
test: drop PackageKit state on Arch Linux

The PackageKit state seems to interfere with running tests offline,
most likely caused by PackageKit trying to sync the core.db but getting
stuck as there is no internet. Therefore it contains an empty file
/var/lib/PackageKit/alpm/sync/core.db.part.

martinpitt/cockpit,martinpitt/cockpit,cockpit-project/cockpit,martinpitt/cockpit,martinpitt/cockpit,cockpit-project/cockpit,cockpit-project/cockpit,cockpit-project/cockpit,martinpitt/cockpit,cockpit-project/cockpit