Stop hardcoding carrier for some regions (bug 1061716)

https://bugzilla.mozilla.org/show_bug.cgi?id=1061716

This was introduced in 2f67a82 to be more more DRY, but it was wrong in some cases: for instance, it meant your carrier was automatically set to 'deutsche_telekom' if you had an US SIM.

Also took the time to sort the 2 arrays by MCC.
I don't see `231` defined in [`regions`](#diff-5f4af35c88476ad1d7655a54cda4e060R30)