DataLabel font was always returning to the default - black.

Change-Id: I6c72a8daa699394b36f69fc54e0ba042f0255c18
Reviewed-on: https://gerrit.libreoffice.org/56616
Tested-by: Jenkins
Reviewed-by: Justin Luth <justin_luth@sil.org>
Reviewed-by: Szymon Kłos <szymon.klos@collabora.com>