Feature: Remove "Connection State" and "Last status update" columns

[Metal-Mighty]

Is your feature request related to a problem? Please describe.
Connection State only shows a "Connected" status when there is an open connection between the edgeHub and the IoT Hub, which is usually only the case for a few minutes. Therefore the sensor will be shown as disconnected most of the time if it only sends data every now and then (every 30min, 1h, ...). It creates confusion for the users who think the devices aren't working anymore.

Last status update is only updated when the Device Twin is updated, which isn't very helpful and creates more confusion among users.

Describe the solution you'd like
Remove the columns.

Describe alternatives you've considered
We tried making the timeouts longer before a connection is closed but it has side effects on their stability and isn't reliable.

Additional context
We are working with LoRaWAN which means that we only send data every few minutes, up to once every day, so most of our sensors are always shown as offline, which confuses non-technical users and ask us for unneeded support.

[Metal-Mighty]

@kbeaugrand As discussed before, would you want to update the data from another source rather than just deleting it altogether? Since we have the ability to subscribe to incoming payloads from Azure IoT Hub, and linking them to devices (RSSI/LSNR signal quality), we could use that timestamp to update these columns.

I don't know if AWS would provide us the same ability though.

[judramos]

Should use lastActivityTime field to replace the last status update and delete the connection state (in devices & gateways)