fdo#54361: Chart background in XLSX is transparent instead of white

Cherry-picked from
53b9adc135f4abb086c740582e5f85cea710287d
and
6d3269ad94bbad8abae5703edc86d8888356bf14

Change-Id: I96d86854484deb7b5c0b99739fed60a430f2f957
Reviewed-on: https://gerrit.libreoffice.org/10468
Reviewed-by: Andras Timar <andras.timar@collabora.com>
Tested-by: Andras Timar <andras.timar@collabora.com>