Upgrade to Elasticsearch 8.18.0

Closes gh-45447

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/data/elasticsearch/ElasticsearchReactiveHealthIndicator.java

@@ -67,8 +67,7 @@ public class ElasticsearchReactiveHealthIndicator extends AbstractReactiveHealth
 			builder.withDetail("number_of_pending_tasks", response.numberOfPendingTasks());
 			builder.withDetail("number_of_in_flight_fetch", response.numberOfInFlightFetch());
 			builder.withDetail("task_max_waiting_in_queue_millis", response.taskMaxWaitingInQueueMillis());
-			builder.withDetail("active_shards_percent_as_number",
-					Double.parseDouble(response.activeShardsPercentAsNumber()));
+			builder.withDetail("active_shards_percent_as_number", response.activeShardsPercentAsNumber());
 			builder.withDetail("unassigned_primary_shards", response.unassignedPrimaryShards());
 			return builder.build();
 		}

spring-boot-project/spring-boot-dependencies/build.gradle

@@ -333,7 +333,7 @@ bom {
 			releaseNotes("https://github.com/ehcache/ehcache3/releases/tag/v{version}")
 		}
 	}
-	library("Elasticsearch Client", "8.17.4") {
+	library("Elasticsearch Client", "8.18.0") {
 		prohibit {
 			contains "-alpha"
 			contains "-beta"