Improve multiple areas PRs with user friendly subs

This applies the same user friendly areas substitutions to the multiple
areas entries that it was already applied to single area entries.

As a bonus, add a case insensitive string sorting that avoids
exponential string allocation.

hack/tools/release/notes.go

@@ -175,6 +175,10 @@ func getAreaLabel(merge string) (string, error) {
 	var areaLabels []string
 	for _, label := range pr.Labels {
 		if area, ok := trimAreaLabel(label.Name); ok {
+			if userFriendlyArea, ok := userFriendlyAreas[area]; ok {
+				area = userFriendlyArea
+			}
+
 			areaLabels = append(areaLabels, area)
 		}
 	}
@@ -183,13 +187,9 @@ func getAreaLabel(merge string) (string, error) {
 	case 0:
 		return missingAreaLabelPrefix, nil
 	case 1:
-		area := areaLabels[0]
-		if userFriendlyArea, ok := userFriendlyAreas[area]; ok {
-			area = userFriendlyArea
-		}
-		return area, nil
+		return areaLabels[0], nil
 	default:
-		return multipleAreaLabelsPrefix + strings.Join(areaLabels, "|") + "]", nil
+		return multipleAreaLabelsPrefix + strings.Join(areaLabels, "/") + "]", nil
 	}
 }
 
@@ -371,6 +371,7 @@ func run() int {
 				str2 := strings.ToLower(mergeslice[j])
 				return str1 < str2
 			})
+
 			for _, merge := range mergeslice {
 				fmt.Println(merge)
 			}