replace stringbuilder with string

Author: nilsbehlen

src/main/java/org/privacyidea/Endpoint.java

@@ -122,9 +122,7 @@ void sendRequestAsync(String endpoint, Map<String, String> params, Map<String, S
                        {
                            if (k.equals("pass") || k.equals("password"))
                            {
-                               StringBuilder tmp = new StringBuilder();
-                               tmp.append("*".repeat(v.length()));
-                               v = tmp.toString();
+                               v = "*".repeat(v.length());
                            }
 
                            privacyIDEA.log(k + "=" + v);