[ticket/13221] Perform bot updates after user table changes

PHPBB3-13221
[ticket/13221] Add bot_update as a dependency to gold

PHPBB3-13221
[ticket/13223] Fix USERNAME email template variable in notification

admin_activate_user.php notification type is assigning usernames to email
template variables using user_loader->get_username() in 'no_profile' mode,
which in its turn calls get_username_string() function in 'no_profile' mode.
This causes HTML markup in emails for username colour.

PHPBB3-13223