chart2: fix the testDataLabelBordersDOCX on Mac

This test failed on Mac because it depends on the layout being finished,
since for SwXTextEmbeddedObjects the corresponding SwVirtFlyDrawObj are
inserted in the draw page not on import, but in layout.

Change-Id: I731b9b92838252ff50135f97343357992bc1933f
svx: little more verbose exception message

Change-Id: I93d5d899fa073cd7ed18e9176b50679b0be95f70