Start building against Spring Kafka 2.7.0 snapshots

See gh-25930

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/kafka/KafkaProperties.java

@@ -1264,7 +1264,7 @@ public class KafkaProperties {
 		/**
 		 * Cleanup the application’s local state directory on shutdown.
 		 */
-		private boolean onShutdown = true;
+		private boolean onShutdown = false;
 
 		public boolean isOnStartup() {
 			return this.onStartup;

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

@@ -1649,7 +1649,7 @@ bom {
 			]
 		}
 	}
-	library("Spring Kafka", "2.7.0-RC1") {
+	library("Spring Kafka", "2.7.0-SNAPSHOT") {
 		group("org.springframework.kafka") {
 			modules = [
 				"spring-kafka",