Adjust for the splitting of number format properties in chart.

Since 1d38cb365543924f9c50014e6b2227e77de1d0c9, "number format" and
"link number format to source" properties are 2 separate properties.  Adjust
OOXML import code for that split.

Also, always set axis' number format via NumberFormat property even when it's
a percent format.  The axis object doesn't keep a non-percent and percent
number formats separately.

Change-Id: I8667b6f1a78d88cc37d059518919ad1b37f154e1
(cherry picked from commit af5a6615dfdbe5c2cacdcacb00fc6f418b925c06)
Reviewed-on: https://gerrit.libreoffice.org/10123
Reviewed-by: Matúš Kukan <matus.kukan@collabora.com>
Tested-by: Matúš Kukan <matus.kukan@collabora.com>