Remove of invisible content has influence on page count and
therefore on fields for page count. So straight after removing
invisible content in the mail merge process, the layout has to
be updated before fields are converted to text.

Change-Id: If43f9921b6797c7ceb112860cda4baf4978c36bc
Reviewed-on: https://gerrit.libreoffice.org/67343
Tested-by: Jenkins
Reviewed-by: Michael Stahl <Michael.Stahl@cib.de>