Check traffic statistics on dormancy status reports
Currently, we bump the traffic statistics polling timeout from 30 sec to 5 min, to minimize unnecessary modem & USB wake ups.
This can be done better though - since the modem already sends us Dormancy Status events indicating whether data channel becomes active or idle, we could only request statistics while traffic channel is active (plus also request it each time we get a "traffic-channel-dormant" event, which would even improve data resolution basically for free).
See also: https://gitlab.freedesktop.org/mobile-broadband/ModemManager/-/issues/287