It seems like Writer default values for table positioning
differ from OOXML spec. if nothing is given.
So write them anyway during export.

Change-Id: If5bf77de71b457a826be8f1559212e7d06c5237c
Reviewed-on: https://gerrit.libreoffice.org/73402
Tested-by: Jenkins
Reviewed-by: Patrick Jaap <patrick.jaap@tu-dresden.de>