Use is{Left,Right}Aligned instead of is{First,Last}. In multi-line
tabs, not only first/last item needs to be drawn differently, but
also some middle, which is now the first in the new line now.

Change-Id: I81ddde192eca794f16df98d629f47991c59732c7
Reviewed-on: https://gerrit.libreoffice.org/68945
Tested-by: Jenkins
Reviewed-by: Tomaž Vajngerl <quikee@gmail.com>