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.
`2  	O2 UK Ltd	O2` as `telefonica`?
`15  	Vodafone Ltd	Vodafone` as `deutsche_telekom`?
`30  	Everything Everywhere Ltd	T-mobile` as `deutsche_telekom`?
`91  	Vodafone United Kingdom	Vodafone` as `deutsche_telekom`?