Close JestClient on shutdown

Closes gh-7051

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/elasticsearch/jest/JestAutoConfiguration.java

@@ -56,7 +56,7 @@ public class JestAutoConfiguration {
 		this.gsonProvider = gsonProvider;
 	}
 
-	@Bean
+	@Bean(destroyMethod = "shutdownClient")
 	@ConditionalOnMissingBean
 	public JestClient jestClient() {
 		JestClientFactory factory = new JestClientFactory();