graph: set max width for legend tables.

ref #2385

public/sass/components/_panel_graph.scss

@@ -133,6 +133,9 @@
     padding-left: 7px;
     text-align: left;
     width: 95%;
+    max-width: 650px;
+    text-overflow: ellipsis;
+    overflow: hidden;
   }
 
   .graph-legend-series:nth-child(odd) {
@@ -264,7 +267,10 @@
   .graph-tooltip-series-name {
     display: table-cell;
     padding: 0.15rem;
-  }
+    max-width: 650px;
+    text-overflow: ellipsis;
+    overflow: hidden;
+   }
 
   .graph-tooltip-value {
     display: table-cell;