Replace scheduleAtFixedRate with scheduleWithFixedDelay

Replace scheduleAtFixedRate with scheduleWithFixedDelay

ScheduledExecutorService.scheduleAtFixedRate tends to run enormous
amounts of runnables that would have been scheduled during a machine is
in sleep, after the machines wakes up from sleep, retroactively.

This is not good and can be avoided by using scheduleWithFixedDelay
which is usually good enough regarding the delay between executions.

gitlab #531

Change-Id: I4ac3b11f1f9236d411debb352fce610c33410659
(cherry picked from commit 00a0eae4da98b701fa38a6813b1743b754c5c99e)