[web/views/formrenderer] remove `cubicweb:target` attribute on form once the target <iframe> is inserted For some unknown reason, IE9 does not want to submit the form inside the <iframe> when the ``cubicweb:target`` attribute exists. (closes #5377672)

cubicweb-web: embedded-javascript-library usr/share/cubicweb/cubes/shared/data/jquery.js