Adapt RestTemplate factory auto-detection

This commit adapts the auto-detection of `ClientHttpRequestFactory` to
look for an httpclient5 class.

See gh-32461

Author: bclozel

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

@@ -38,7 +38,7 @@
  */
 public class ClientHttpRequestFactorySupplier implements Supplier<ClientHttpRequestFactory> {
 
-	private static final String APACHE_HTTP_CLIENT_CLASS = "org.apache.http.client.HttpClient";
+	private static final String APACHE_HTTP_CLIENT_CLASS = "org.apache.hc.client5.http.impl.classic.HttpClients";
 
 	private static final boolean APACHE_HTTP_CLIENT_PRESENT = ClassUtils.isPresent(APACHE_HTTP_CLIENT_CLASS, null);