tdf#134548: sw: revert of changes to tab at zero pos
It looks like solution for provided in 5ed96c for
tdf#83309 is enough to resolve original bugdoc, so
these changes for emission of tab at zero position
are not required and produce just regressions.
Corresponding unittest for tdf#83309 is adjusted: it
is using now original bugdoc.
Change-Id: I2e7683f071f78c720436b4c9ccb903133a985e7c
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/98476
Tested-by: Jenkins
Reviewed-by: Thorsten Behrens <Thorsten.Behrens@CIB.de>