xk6-disruptor-agent does not terminate if test is cancelled

[pablochacin]

When a failure is injected in a Pod, xk6-disruptor executes the xk6-disruptor-agent as a process int the xk6-agent container attached to that Pod. Is this process which injects the disruption in the Pod.

If the k6 test is cancelled, this process is not cancelled and the disruption continues in effect until the process ends.

Running again the test while this process is running will have unpredictable results.

To address this issue we need to

• Handle the termination of the test. This is presently not possible due to Hooks for extensions - e.g. graceful shutdown, per VU/iteration, etc. k6#2432
• Cancel the execution of the command. This may require cancelable exec connections which is planned in kubernetes client 0.26.