test: Skip TestStoragePackagesNFS.testNfsMissingPackages on arch
test: Skip TestStoragePackagesNFS.testNfsMissingPackages on arch

All the other PackageKit related tests are skipped on arch
(check-packagekit, check-apps, TestMetricsPackages, etc.) as the current
mechanism of creating, installing, and cleaning up fake packages is
buggy.

Skip this test as well, as it runs into similar issues.

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