test: Fix race condition in TestStorageVDO.testVdo
test: Fix race condition in TestStorageVDO.testVdo

It sometimes happens that the UI only sees the VG, but not the newly
created LV yet. Then the "create VDO" dialog shows "No disks available".

Wait for the LV to appear to fix that.

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