Unit-tests, which schedule asynchronous work through NetworkTestEnv::launchAsync currently wait for up to 15 seconds for that work to complete.

On DEBUG builds and on slower Evergreen machine variants we have seen this async work take more than 15 seconds, causing the unit-tests to fail. In order to avoid these intermittent failures, we should increase this default timeout to be on the order of a few minutes (I'd say 5 minutes is a good round number).