remove obsolete resizer

res/css/structures/_RoomSubList.scss

@@ -25,11 +25,6 @@ limitations under the License.
     min-height: unset;
 }
 
-.mx_RoomSubList_resizer {
-    width: 100%;
-    height: 3px;
-    background-color: $roomsublist-background;
-}
 
 .mx_RoomSubList_labelContainer {
     display: flex;

src/components/structures/RoomSubList.js

@@ -394,7 +394,6 @@ const RoomSubList = React.createClass({
                 <div className="mx_RoomSubList">
                     {this.props.alwaysShowHeader ? this._getHeaderJsx() : undefined}
                     { this.state.hidden ? undefined : content }
-                    <div className="mx_RoomSubList_resizer"></div>
                 </div>
             );
         }