Fix some number format issues, bnc#862510

Set "LinkNumberFormatToSource" to false, so that format code is not
ignored.
Also, do not inherit format code common for all labels, if there is
specific format code for a data label.

Change-Id: I505311d5df641d61e616e354734bd332609fa122
(cherry picked from commit c8cc89ff802d86b1f3a69afe1b4835b7df7f70c7)
Reviewed-on: https://gerrit.libreoffice.org/10780
Reviewed-by: David Tardon <dtardon@redhat.com>
Tested-by: David Tardon <dtardon@redhat.com>