statusicon: Create pixbuf at correct size

Surface returned from gtk_icon_helper_load_surface can be smaller
then requested pixel size. This happens when icon is embedded in
panel that has bigger size then loaded pixbuf.
2 jobs for wip/muktupavels/gtk-status-icon in 8 minutes and 11 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Build
passed #166953
build

00:08:11

manual #166954
win32 allowed to fail manual
msys2-mingw32