fix: ensure widget size is set correctly on linux on small screens (#28756)

When creating a widget on linux the bounds are restricted to the screen
size, when calling SetSize / SetBounds they are not.  This fixes this
initialization issue by calling SetBounds after widget creation.

Noticed this issue while running linux tests on xvfb with a screen size
smaller than the default electron window size (resulted in a failed
test).

Co-authored-by: Samuel Attard <samuel.r.attard@gmail.com>