Restore enableAssociationManagement for Hibernate

This is enabled on Gradle side too, so maybe we shouldn't drop it without further investigation.

See gh-1990

Author: mhalbritter

start-site/src/main/java/io/spring/start/site/extension/dependency/graalvm/HibernatePluginMavenBuildCustomizer.java

@@ -44,7 +44,8 @@ public void customize(MavenBuild build) {
 		if (isSpringBoot4OrLater()) {
 			build.plugins()
 				.add("org.hibernate.orm", "hibernate-maven-plugin", (plugin) -> plugin.version("${hibernate.version}")
-					.execution("enhance", (execution) -> execution.goal("enhance")));
+					.execution("enhance", (execution) -> execution.goal("enhance")
+						.configuration((configuration) -> configuration.add("enableAssociationManagement", "true"))));
 		}
 		else {
 			build.plugins()

start-site/src/test/java/io/spring/start/site/extension/dependency/graalvm/GraalVmProjectGenerationConfigurationTests.java

@@ -126,6 +126,9 @@ void mavenBuildWithJpaConfigureHibernateEnhancePlugin() {
 				"						<goals>",
 				"							<goal>enhance</goal>",
 				"						</goals>",
+				"						<configuration>",
+				"							<enableAssociationManagement>true</enableAssociationManagement>",
+				"						</configuration>",
 				"					</execution>",
 				"				</executions>",
 				"			</plugin>");