test: Mark TestPinger as nondestructive
test: Mark TestPinger as nondestructive

It already DTRT, we just forgot to label it.

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