Print useful message when trying to start watchdog with broken replication

When any of the slave threads are stopped on secondary and WATCHDOG_ENABLE file is present under HA directory, if we try to start the watchdog it just hangs and times out. It needs to present a useful error message on the command line in this case.

**Reproduce steps:**
1) touch WATCHDOG_ENABLED in HA folder
2)login to db and stop any thread.
stop slave IO_THREAD;
exit
3) try to start service appdcontroller start, this command just times out.