fdo#85046 removing extra merge document entry in the Tools menu

Change-Id: Ia3690a4fa539cbfcfe03a70cdb467ee4cf7cb1e3
Reviewed-on: https://gerrit.libreoffice.org/12331
Reviewed-by: Samuel Mehrbrodt <s.mehrbrodt@gmail.com>
Tested-by: Samuel Mehrbrodt <s.mehrbrodt@gmail.com>