_ows_check_services_running was made public without the underscore and
it's private function name was made an alias and marked deprecated by:
https://github.com/juju/charm-helpers/pull/658
Switch to the new name to avoid many deprecation warnings being printed
by dependant charms every time update-status hooks run:
DEPRECATION WARNING: Function _ows_check_services_running is being
removed on/around 2022-05 : use ows_check_services_running() instead
Change-Id: I4758330db81a95ac2aa17f9bc316afdc2eab2d44