Made is_server_running() function in backup_functions.sh aware of
the nuances of of checking whether p4broker, p4d, and p4p are up.
For the broker in particular, only the default broker configuration
is checked. This will avoid process compatibility issues with customers
using DFM (Down for Maintenance) brokers as part of the upgrade
procedure, either manually or with the Helix Management System (HMS).
This was done by deferring to the *_base scripts for each service
type, as these scripts now return reliable exit codes for status.
Made p4d_base not write anything to p4d_init.log if only a 'status'
check is done.
Fixed bug in 'p4d base' status check where it would return a wrong
exit code if p4d was up but SSL trust was not established. Removed
redundant logic in start_p4[d,p,broker] functions for service status