ExecutionTest#shouldSupportMaxDuration() breaks because of indeterministic scheduling

[failsafe-lib]

ExecutionTest#shouldSupportMaxDuration() breaks because of indeterministic scheduling

[jhalterman]

I'm fine with option 1 for a few reasons:

• It keeps the tests simple and easy to read, so someone browsing the code can easily understand what the test is trying to do.
• It's similar to what we're doing in various other tests (for better or worse, right now).

I'm open to improving things more substantially throughout the test suite, but readability/simplicity of the tests is somewhat important.

[leozilla]

I am also fine with option 1. Just wanted to point out some possibilities.
A PR follows in the upcoming days.

[jhalterman]

Cool, thanks.

[jhalterman]

@leozilla I just went ahead and did this since I hadn't heard back from you :)