Missing environment variable option to disable telemetry

[sebws]

In SST v2, you were able to disable telemetry through an environment variable which is a relatively standard way of doing it.

I've opened #1152 to address this. At the moment this is reusing the old environment variable name which seems appropriate to me.

I think it would be good to add DO_NOT_TRACK as an option as well, see https://consoledonottrack.com/