Investigate network ID feature in ESR 52
Mozilla landed a network identification ID feature in Firefox 49 (https://bugzilla.mozilla.org/show_bug.cgi?id=1240932). We probably don't want that. At least we should investigate it closer and maybe don't let an ID get computed at least when Telemetry is disabled.
Note: this has probably consequences for (Linux) sandboxing at least as it needs access to /proc/net/arp.