Use 'centralauth-state-mismatch' message in adminLock() and adminUnlock()
Initially, this was supposed to be shown when non-existent global accounts
were (un)locked but then the i18n messages got removed in a redesign commit.
Rather than adding the messages again, it's better to reuse the message
'centralauth-state-mismatch' instead as it is very unlikely for non-existent
global accounts to reach adminLock() and adminUnlock() when compared to