Increase the worker detection timeout.
Increase the worker detection timeout.

In some unusual cases, worker nodes may take more than two seconds to
respond when returning their list of tools. This could cause the UI to
show that there are no active worker nodes, even though the worker is
running and connected to the broker. This change increases the timeout.

Testing done:
Looked at the Review Bot admin UI and deteecteed running worker nodes.

Reviewed at https://reviews.reviewboard.org/r/10080/

reviewboard/ReviewBot,reviewboard/ReviewBot,reviewboard/ReviewBot,reviewboard/ReviewBot