fix(dashboard): chart yAxis calculation (#929)

Because

currently the triggered count was getting overwritten by next value.
```
 yAxis[pipelineIndex]["data"][xAxisIndex] = pipeline.trigger_counts[bucketIndex];
```

This commit

it should be, if their is already a value, to the index, it should add
up to the previous value
```
if (yAxis[pipelineIndex]["data"][xAxisIndex]) {
        yAxis[pipelineIndex]["data"][xAxisIndex] += pipeline.trigger_counts[bucketIndex];
   } else {
       yAxis[pipelineIndex]["data"][xAxisIndex] += pipeline.trigger_counts[bucketIndex];
}
```

packages/toolkit/src/lib/dashboard/generateChartData.ts

@@ -42,8 +42,13 @@ export function generateChartData(
     ].entries()) {
       const xAxisIndex = xAxis.findIndex((date) => date === formattedBucket);
       if (xAxisIndex !== -1) {
-        yAxis[pipelineIndex]["data"][xAxisIndex] =
-          pipeline.trigger_counts[bucketIndex];
+        if (yAxis[pipelineIndex]["data"][xAxisIndex]) {
+          yAxis[pipelineIndex]["data"][xAxisIndex] +=
+            pipeline.trigger_counts[bucketIndex];
+        } else {
+          yAxis[pipelineIndex]["data"][xAxisIndex] +=
+            pipeline.trigger_counts[bucketIndex];
+        }
       }
     }
   });