Don't use net.bytebuddy.experimental=true for Java 23 testing

Should have been part of a previous Bytebuddy upgrade, but it seems we
forgot.

Jenkinsfile

@@ -36,6 +36,7 @@ stage('Configure') {
 		// even if we don't use these features, just enabling them can cause side effects
 		// and it's useful to test that.
 		new BuildEnvironment( testJdkVersion: '23', testJdkLauncherArgs: '--enable-preview' ),
+		new BuildEnvironment( testJdkVersion: '23', testJdkLauncherArgs: '--enable-preview' ),
 		// The following JDKs aren't supported by Hibernate ORM out-of-the box yet:
 		// they require the use of -Dnet.bytebuddy.experimental=true.
 		// Make sure to remove that argument as soon as possible