We already deduplicated first line indentation since commit
3915bf2d (tdf#95376 DOCX import: fix
incorrectly indented tab stops, 2016-01-26), the same is necessary for
before text indent.

Change-Id: I11394881d116f76922c1a706dd14b6a7cdf3c89f
Reviewed-on: https://gerrit.libreoffice.org/45844Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Jenkins <ci@libreoffice.org>