in the files generated in /opt/otrs/Kernel/Language/*.pm, there is a translation autogenerated :
Trying to edit it in a *_Custom.pl file doesn't change anything, as if it didn't match.'*** out of office until %s (%s d left) ***' => '',
Would there be something missing ? (%d for some string before and/or after ? Escape characters before * ?)
In all cases, this translation isn't working...