dashboard/app: enable coverage pages formatting

cover.Format controls the resulting view.
It allows to:
1. Remove records with 0 covered blocks.
2. Remove lines with low (user defined) coverage.
3. Order records by the covered lines drop value.

The corresponding GET parameters are:
1. Implicitly enabled for onlyUnique records.
2. min-cover-lines-drop=%d
3. order-by-cover-lines-drop=1

Author: tarasmadan

dashboard/app/coverage.go

@@ -121,10 +121,6 @@ func handleHeatmap(c context.Context, w http.ResponseWriter, r *http.Request, f
 
 	onlyUnique := r.FormValue("unique-only") == "1"
 	orderByCoverLinesDrop := r.FormValue("order-by-cover-lines-drop") == "1"
-	minPercentDrop, err := strconv.Atoi("0" + r.FormValue("min-percent-drop"))
-	if err != nil {
-		return fmt.Errorf("min-percent-drop should be integer")
-	}
 	minCoverLinesDrop, err := strconv.Atoi("0" + r.FormValue("min-cover-lines-drop"))
 	if err != nil {
 		return fmt.Errorf("min-cover-lines-drop should be integer")
@@ -141,7 +137,6 @@ func handleHeatmap(c context.Context, w http.ResponseWriter, r *http.Request, f
 		},
 		onlyUnique, subsystems, managers,
 		cover.Format{
-			FilterMinPercentDrop:      minPercentDrop,
 			FilterMinCoveredLinesDrop: minCoverLinesDrop,
 			OrderByCoveredLinesDrop:   orderByCoverLinesDrop,
 			DropCoveredLines0:         onlyUnique,

pkg/cover/heatmap_test.go

@@ -156,6 +156,7 @@ func TestFilesCoverageToTemplateData(t *testing.T) {
 	}
 }
 
+// nolint: dupl
 func TestFormatResult(t *testing.T) {
 	tests := []struct {
 		name   string