Avoid unnecessary reflection in builders

Closes gh-23560

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/client/RestTemplateBuilder.java

@@ -586,7 +586,7 @@ public class RestTemplateBuilder {
 	 * @see #configure(RestTemplate)
 	 */
 	public RestTemplate build() {
-		return build(RestTemplate.class);
+		return configure(new RestTemplate());
 	}
 
 	/**

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/webservices/client/WebServiceTemplateBuilder.java

@@ -424,7 +424,7 @@ public class WebServiceTemplateBuilder {
 	 * @see #configure(WebServiceTemplate)
 	 */
 	public WebServiceTemplate build() {
-		return build(WebServiceTemplate.class);
+		return configure(new WebServiceTemplate());
 	}
 
 	/**