Re-scale the primary Y axis if the secondary axis
is deleted and the dataseries still attached to the
secondary axis.

Change-Id: I6e7958766d23a74569ce8529ddf1bdafa89f1870
Reviewed-on: https://gerrit.libreoffice.org/71302
Tested-by: Jenkins
Reviewed-by: László Németh <nemeth@numbertext.org>