Schedule generation was broken

Only one schedule entry was generated at schedule generation because of this `return;`.

fixes #4173

Author: Anton Evers

app/code/Magento/Cron/Observer/ProcessCronQueueObserver.php

@@ -486,7 +486,6 @@ protected function saveSchedule($jobCode, $cronExpression, $timeInterval, $exist
             if ($schedule->trySchedule()) {
                 // time matches cron expression
                 $schedule->save();
-                return;
             }
         }
     }