nut: prevent service thrashing on boot or hotplug

nut: prevent service thrashing on boot or hotplug

On boot, hotplug events were causing excessive start and stop action
for the upsd daemon and driver daemons. We fix that with two primary
actions:
  1. Don't restart service daemons on hotplug until after first boot
     has completed.
  2. Use more robust handling of procd instance starts by ensuring
     that the first start starts the nut-server service and all
     others add to the nut-server service (rather than replacing it).

Ignore hotplug events without a DEVNAME.

In addition clean up some logging.

In the process, this fixes #30375 "hotplugging for setting usb access
right[s] doesn't work anymore"

Closes: #30375
Signed-off-by: Daniel F. Dickinson <redacted>