Set the new driver url and start the thread if not already started
This should be called only when the process is terminating.
This should be called only when the process is terminating. If a process ceases to be an executor, only startOrTransmuteExecutor should be called with None.
This class is responsible for initiating the executor process inside the jvm. Also, if an executor has to be stopped, driverURL can be set as None and it will take care of stopping the executor.