pyuno: Use appropriate OUString functions on string constants
pyuno: Use appropriate OUString functions on string constants

Change-Id: Ib507da6fc85d8bc81fd48108a98ef96d188643ac

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