Fix PDF label when exporting a picture file

When trying to export a picture file with converting it to PDF when we go to export the label that appears for that action is exportButton.imageToPDF instead of PDF like in the other documents

How to reproduce

• have webui and dam packages installed
• open webui and create a picture file
• go to the file actions, click on the 3 dots icon(right top of the screen) and then click on Export in the popup(wrong PDF label appears)