Would be "HTML" by default, but reqif-html is mostly very simple
documents and the custom page styles is unexpected.

Change-Id: I3f1b293bcd074305cf5cc87f03248e934d5fac4d
Reviewed-on: https://gerrit.libreoffice.org/62317Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Jenkins