[FIX] web: statusbar margins in in-dialog form views

Form views with a chatter in a dialog on a large screen are styled by
the side chatter feature. This is not a problem as it is made to be
automatically adapted whether a chatter is displayed or hidden, but
in-dialog only rules had to be adapted.

addons/web/static/src/less/form_view.less

@@ -604,6 +604,10 @@
         .o_form_sheet_bg {
             padding: 0;
 
+            > * {
+                margin: 0;
+            }
+
             > .o_form_sheet {
                 box-shadow: none;
                 width: 100%;