Now that we use setproctitle for neutron-server workers (and
neutron-keepalived-state-change), this has the side effect of changing
the process name for agents, impacting some monitoring systems. More
details in launchpad bug.
This patch fixes it by setting the name with setproctitle to:
agent name (original process name).
Also use the newly introduced name constants to replace existing
hardcoded uses.
Change-Id: I74c3a4d3e9f833752571a75f196560cd45529385
Closes-Bug: #1881297