Reuse node to prevent overwriting channel settings

[lysol]

Hi!

I noticed that I'm unable to use any --ch-set settings over the admin channel (using --dest). The core issue is that the repeated use of interface.getNode fetches all the channels again, overwriting the channels on the node object that had just been retrieved and updated to change the appropriate settings. This means that downlink_enabled, uplink_enabled, and so on couldn't actually be updated using remote admin. I've confirmed this change allowed me to change MQTT uplink/downlink on a remote node on a tall rooftop.

I attempted to use requestChannels in getNode but the repeated usage of getNode itself blows away the channels on the object, regardless.

[CLAassistant]

All committers have signed the CLA.

[ianmcorvidae]

This looks great to me. Should also remove a full cycle of requesting channels from these commands, not that they were working before anyway 😅

[ianmcorvidae]

(setting CI to run in case it finds anything that needs updating, but other than if it does, ready to merge I'd say)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 61.68%. Comparing base (bcce568) to head (aed4f25).
Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #664      +/-   ##
==========================================
+ Coverage   61.67%   61.68%   +0.01%     
==========================================
  Files          24       24              
  Lines        3593     3594       +1     
==========================================
+ Hits         2216     2217       +1     
  Misses       1377     1377              

Flag	Coverage Δ
unittests	61.68% <100.00%> (+0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.