[Platform] Health-check script generates an alert for 2.5.x when using Python 3

[SergeyPotachev]

multiprocessing.pool.RemoteTraceback:
"""
Traceback (most recent call last):
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/multiprocessing/pool.py", line 121, in worker
result = (True, func(*args, **kwds))
File "bin/cluster_health.py", line 446, in multithreaded_caller
return getattr(instance, func_name)(*args, **kwargs)
File "bin/cluster_health.py", line 315, in check_uptime_for_process
uptime = self.get_uptime_for_process(process)
File "bin/cluster_health.py", line 310, in get_uptime_for_process
return self._remote_check_output(remote_cmd).strip()
File "bin/cluster_health.py", line 233, in _remote_check_output
if output.endswith('No route to host'):
TypeError: endswith first arg must be bytes or a tuple of bytes, not str
"""

The script requires small update.

[SergeyPotachev]

One more stack trace for Python 3:

Traceback (most recent call last):
File "bin/cluster_health.py", line 605, in
main()
File "bin/cluster_health.py", line 589, in main
entries = coordinator.run()
File "bin/cluster_health.py", line 488, in run
" for check " + check.func_name)