fix(graph): sets legend table scroll to auto

closes #4760

public/sass/components/_panel_graph.scss

@@ -85,7 +85,8 @@
 }
 
 .graph-legend-table {
-  overflow-y: scroll;
+  overflow-y: auto;
+  overflow-x: hidden;
 
   .graph-legend-series {
     display: table-row;