Draw/Impress: thumbnails or pages drawn with grid or slide placeholders

[hfiguiere]

Describe the Bug

In Impress, the thumbnails are drawn with the grid (if enabled) or the placeholders from the master.
In Draw, pages drawn with the grid.

Steps to Reproduce

1. In Impress a new document will show the placholders

2. In LibreOffice create a presentation OR a draw document. Display the grid. Save. (Issue Draw: Display Grid #7406 is why we can't toggle the grid display)

3. Open the document in Online

Expected Behavior

Slide placeholder shouldn't be draw in the thumbnails. Nor the grid.

Actual Behavior

Placeholder aren't draw. Grid isn't drawn.

Screenshots

If applicable, add screenshots to help explain your problem.

Desktop

(Please complete the following information)

• Collabora version: master
• Browser: Firefox.

Additional Context

[hfiguiere]

Temporary work around for the Grid:
https://gerrit.libreoffice.org/c/core/+/167872