fix: update histogram plotting to skip negative values

Author: tosettil-polimi

pkg/coordinator/utils/hdr/plot.go

@@ -15,7 +15,7 @@ func Plot(data []int64) (string, error) {
 
 	// Add the data to the histogram
 	for _, value := range data {
-		if value <= 0 {
+		if value < 0 {
 			continue
 		}