Polishing.

Rename AssumeConnection to EnabledOnElasticsearch following the typical design of JUnit 5 EnabledOn… annotation programming model. Enable tests by default if the test element isn't annotated with EnabledOnElasticsearch as we assume that the extension was activated by the parent.

Move EnabledOnElasticsearch into utility project.

See #583
Original pull request: #609

elasticsearch/example/pom.xml

@@ -3,7 +3,6 @@
 		 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
 	<modelVersion>4.0.0</modelVersion>
 
-	<groupId>org.springframework</groupId>
 	<artifactId>spring-data-elasticsearch-example</artifactId>
 
 	<name>Spring Data Elasticsearch - Node Client Example</name>
@@ -18,6 +17,11 @@
 
 	<dependencies>
 
+		<dependency>
+			<groupId>org.springframework.data.examples</groupId>
+			<artifactId>spring-data-elasticsearch-example-utils</artifactId>
+		</dependency>
+
 		<dependency>
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-starter-log4j2</artifactId>