Bug 1040271 - [L10n][SMS] Clean up mozL10n.get uses in SMS app

This will make a quite big combinatorial using this logic, and I can't find another simple solution, so maybe we want to keep the previous logic?

Another possibility is to have as locale string the 1, 2 and 3-element forms, and use one or the other depending on `info.length`? AFAIK "SIM" is not translated in any language currently so this is maybe good enough?