fix(e2e): Create next namespace if one exists

 Do not error out if the namespace to run e2e into exists, try creating
 next one in row. Retry at 20 next namespaces, before erroring out.

lib/test/integration.go

@@ -46,13 +46,22 @@ type KnTest struct {
 
 // NewKnTest creates a new KnTest object
 func NewKnTest() (*KnTest, error) {
-	ns := NextNamespace()
-
-	err := CreateNamespace(ns)
-	if err != nil {
-		return nil, err
+	ns := ""
+	// try next 20 namespace before giving up creating a namespace if it already exists
+	for i := 0; i < 20; i++ {
+		ns = NextNamespace()
+		err := CreateNamespace(ns)
+		if err == nil {
+			break
+		}
+		if strings.Contains(err.Error(), "AlreadyExists") {
+			continue
+		} else {
+			return nil, err
+		}
 	}
-	err = WaitForNamespaceCreated(ns)
+
+	err := WaitForNamespaceCreated(ns)
 	if err != nil {
 		return nil, err
 	}