drawingML: remove code duplication: use WriteStretch()
drawingML: remove code duplication: use WriteStretch()

Change-Id: I0d589da01bf6afed86b5811d6b27f72f6e1bb160

JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core