[ticket/11973] Remove logic from tokens language array

Previously if a translator did no translate a token, it would not be
displayed. On the other hand, the translator could add additional tokens
which have no functionality.  Functionality is already hardcoded into
bbcode.php so we can that in the ACP aswell, in order to prevent namend
issues.

PHPBB3-11973
Merge remote-tracking branch 'nickvergessen/ticket/11973' into develop

# By Joas Schilling
# Via Joas Schilling
* nickvergessen/ticket/11973:
  [ticket/11973] Remove logic from tokens language array