Do not show dialog when reloading file that requests fullscreen

When using Okular as previewer in PDFTex workflow, preparing beamer slides,
the following usability hell occurred:

• LaTex/Beamer slides should be compiled to PDF with metadata "StartFullScreen"
• But while editing, on every PDF change/and reload, the user gets a modal popup "The document requested to be launched in presentation mode." "Do you want to allow it?"

BUG: 361740