Default size of "Export to PDF" dialog too large in 3.10

[ryankdalton]

Describe the bug
The default size of the "PDF Export Options" dialog window is too large for small screens (<= 14"). The new "Create Geospatial PDF" expandable pane in open by default. If it were collapsed by default, the "Save" button would be visible on all screen sizes.

How to Reproduce

1. Open an existing layout
2. Click on 'Export as PDF'
3. Even though the checkbox "Create Geospatial PDF" is ticked off, the pane is fully expanded, pushing the "Save" button off the screen for smaller screen sizes.
4. Having this pane collapsed by default would resolve the problem, or only have the pane expanded if the checkbox is ticked on.

QGIS and OS versions
QGIS 3.10
Windows 10