OO-3187: reverse the check by allowed email in the creation processs of LDAP users

src/main/java/org/olat/ldap/manager/LDAPLoginManagerImpl.java

@@ -535,7 +535,7 @@ public class LDAPLoginManagerImpl implements LDAPLoginManager, GenericEventListe
 			log.error("Cannot try to lookup user " + uid + " by email with an invalid email::" + email, null);
 			return null;
 		}
-		if (userManager.isEmailAllowed(email) ) {
+		if (!userManager.isEmailAllowed(email)) {
 			log.error("Can't create user with email='" + email + "', a user with that email does already exist in OLAT database", null);
 			return null;
 		}