1859260 - Remove references to FxA (Firefox accounts) in sync code

Status: NEW

(Thunderbird :: General, task, P3)

Description

[Brendan Abolivier [:babolivier]]

Firefox accounts are being rebranded to Mozilla accounts on Nov 1st, 2023. We've decided to replace them with a branding-agnostic version ("Firefox account" -> "account") since the user-facing strings don't appear in a context that can be ambiguous.

As of bug 1857555 there isn't any user-facing string that mentions Firefox accounts, but it would be good for maintainability that the code doesn't refer to a dead acronym through symbol names for ages. The new identifiers for the translation strings use "sync" instead of "fxa", so I would suggest we do something similar here.