fix: handle flaky tests

[anonrig]

I still believe fake-timers are the main issue behind this. There are still some other tests being flaky due to fake timers tickAsync. I opened a pull request to discuss a potential solution.

Steps I've taken:

• Understand multiple tests were contradicting each other due to the same port number
• Run the test couple of times, it was still flaky
• Updated sinon fake timers and tap, since the only ambigious side of the test was the fake timers.
• Found the following issue: Using SinonJs fakeTimers with Tap tapjs/tapjs#709
• Changed for loop 10 times tickAsync(1000) with for loop 100 times with tickAsync(100). Which solved the issue on the retry-failed-services.js test.

[mcollina]

lgtm