[ticket/11666] Removing MESSAGE_DELETED..

..in /en/posting.php as it is not used.

PHPBB3-11666
[ticket/11666] Rewording POST_DELETED and

reverting removal of MESSAGE_DELETED.

PHPBB3-1166666666
Merge remote-tracking branch 'suheb/ticket/11666' into develop-ascraeus

* suheb/ticket/11666:
  [ticket/11666] Rewording POST_DELETED and
  [ticket/11666] Removing MESSAGE_DELETED..
Merge branch 'develop-ascraeus' into develop

* develop-ascraeus:
  [ticket/11666] Rewording POST_DELETED and
  [ticket/11666] Removing MESSAGE_DELETED..