Adjust timeouts in LARS tests since processing can take a while. See #3091

So from number 0 in the log output you can see that we managed to cancel 0 of the tasks. This probably means that the machine is heavily loaded and the sleep in the test takes way more than 500 millis.

On my machine if I let all the tasks be scheduled before trying to cancel them. Just processing the resulting messages can take as long as 3.2 seconds.