Problem 1: the running deployments were fetched for every application with a custom timeout of 2 seconds -> moved this as ctor dependency
Problem 2: the mapping from Application to ApplicationWithTask gets the service and taskTracker and can do arbitrary logic -> all dependencies given by ctor
Problem 3: the MarathonScheduler used an arbitrary timeout to acquire a lock per application -> remove the timeout
Problem 4: the MarathonScheduler does a lot in the receive method -> logic is executed inside an async block
Problem 5: the MarathonScheduler blocks until all locks are available, when force is requested -> clarify with DR if this is ok.

MarathonSchedulerActor: remove UpdateApp case, since it is not used anywhere