test: Wait until all keys are available
test: Wait until all keys are available

Test is clicking on the `:last-child`s delete button but it may happen
that the last added slot is not yet shown in the UI and then wrong slot
is removed.

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