Fix empty stacked bar chart for topN hosts

When grouping items into top N buckets, we relied on the existence of
two keys (key and key_as_string) to provide the topN value to the chart.

If "key" was a string type, then we returned the value of
"key_as_string". Otherwise, we returned the value of "key".

However, this assumption no longer applies. The HostID value is an
unsigned long, but only is available in "key" and the "key_as_string"
does not exist.

src/plugins/profiling/common/index.ts

@@ -53,11 +53,7 @@ export function getTopN(obj) {
       const bucket = obj.topN.histogram.buckets[i];
       for (let j = 0; j < bucket.group_by.buckets.length; j++) {
         const v = bucket.group_by.buckets[j];
-        if (typeof v.key === 'string') {
-          data.push({ x: bucket.key, y: v.Count.value, g: v.key });
-        } else {
-          data.push({ x: bucket.key, y: v.Count.value, g: v.key_as_string });
-        }
+        data.push({ x: bucket.key, y: v.Count.value, g: v.key });
       }
     }
   } else if (obj.TopN !== undefined) {