Stop the runner if test time exceeds the duration given #549

[enudler]

Describe the bug
In some configurations the runner keeps sending requests after the test duration is up, in this case the runner should send a DONE stat and the test should be marked as finished

To Reproduce
Steps to reproduce the behavior:

1. Run 2000 RPS test with 1 parallism on a very fast API server(5ms response rate)
2. No avoided scenarios and therefore the runner will keep sending requests after the time is up

Expected behavior

1. Test finish in the expected time duration

Version:

• Predator: 1.6.0
• Predator-runner: 1.6.0

Additional context
Possibility to add this implementation with an environment variable in the predator installation, some users might not want the test to finish and let it keep running