Use hashpipe-redis gateway groups when resetting `DWELL`

[danielczech]

When resetting DWELL to the prior value, use hashpipe-redis gateway groups - currently the log file has an entry for every processing node in the subarray as follows:

[2021-11-02 20:00:35,504 - INFO - coordinator.py:734] Published DWELL=0 to channel bluse://blpn62/0/set
[2021-11-02 20:00:35,504 - INFO - coordinator.py:734] Published PKTSTART=0 to channel bluse://blpn62/0/set
[2021-11-02 20:00:35,605 - INFO - coordinator.py:734] Published DWELL=60 to channel bluse://blpn62/0/set