utils/collectd: run with low priority

utils/collectd: run with low priority

Even on a powerful platform a collectd process'
activities are sometimes affecting throoughput and
latency. This is a backgroud process, that should not
be running with default priority.
Even if it is a little deplayed, that is not a worry in
this case. The routing should be the main priority,
stats collection can wait a bit.

Tested on Netgear R7800
Signed-off-by: Marc Benoit <marcb62185@gmail.com>
Make niceness more moderate, bump version.
Signed-off-by: Hannu Nyman <hannu.nyman@iki.fi>