It's not necessary because we have configured silent printing for
Firefox and Chrome in the browser arguments we pass in `test.mjs`. This
means that the print dialog is not even shown at all or disappears
automatically once printing is done, so the Escape key press serves no
purpose. Since it has been shown to time out, likely because the page
loses focus during printing, and because the page itself doesn't know
when the printing dialog is shown and we therefore can't possibly do the
key press at the right time anyway, this commit gets rid of it to
stabilize the test.
