demo-orgs: Specify email input when rendering add email modal.

There are two inputs for the add email modal in demo organizations,
one to add the email address of the owner and one to update their
full name. We want the email input to be selected when the modal
is opened.

web/src/settings_account.ts

@@ -713,9 +713,7 @@ export function set_up(
                 form_id: "demo_organization_add_email_form",
                 on_click: do_demo_organization_add_email,
                 on_shown() {
-                    ui_util.place_caret_at_end(
-                        util.the($("#demo_organization_add_email_form input")),
-                    );
+                    ui_util.place_caret_at_end(util.the($("input#demo_organization_add_email")));
                 },
                 post_render: demo_organization_add_email_post_render,
             });