Is your feature request related to a problem? Please describe.
Would be safer to construct the Fate objects then call something like fate.start(). Right now, some of the fate threads will be started after a delay, but are scheduled in the constructor. Should be scheduled after construction to avoid any potential problems like leaking this before construction if the threads somehow run before construction completes.

Describe the solution you'd like
fate threads are scheduled in a new method like start() instead of in the constructor. Will need to change all uses of Fate to also call start.

Additional context
Fate constructor is currently leaking this with startFateExecutors(), but this is being removed in #5817.
This ticket should wait until that PR is merged.