Revert "Bug 1023419 - Unify strings in Firefox Accounts and Find my device. r=ggp"

This reverts commit 2f77e2686dcd3964498eaca68b244dc6df8c7bf2.
Merge pull request #20835 from 6a68/revert-bug-1023419-v2.0

Revert "Bug 1023419 - Unify strings in Firefox Accounts and Find my devi...