fdo#44081 don't remove 'edit' pop-up menu entry from form in design mode

Change-Id: I9700d0d729a8f2d1255fcd03a07e05799e21f8d0
Reviewed-on: https://gerrit.libreoffice.org/11152
Reviewed-by: Bosdonnat Cedric <cedric.bosdonnat@free.fr>
Tested-by: Bosdonnat Cedric <cedric.bosdonnat@free.fr>
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>