[FIX] web: display dashboard graphs in full-width

With the new views, the class `o_field_widget` is added on every field widget
and is styled with `display: inline-block`.

The dashboards used to display graphs in full-width so this behaviour is
restored.

addons/web/static/src/less/fields.less

@@ -33,7 +33,7 @@
     }
 
     // Block fields
-    &.note-editor, &.oe_form_field_html, &.oe_form_field_html_text, &.oe_form_field_text, &.o_view_manager_content, &.o_field_domain {
+    &.note-editor, &.oe_form_field_html, &.oe_form_field_html_text, &.oe_form_field_text, &.o_view_manager_content, &.o_field_domain, &.o_graph_linechart, &.o_graph_barchart {
         display: block;
     }