Mail / Log / Remove debug level

Avoid displaying mail server configuration and other detailed information in the log.

```
DEBUG: JavaMail version 1.5.6
DEBUG: successfully loaded resource: /META-INF/javamail.default.providers
DEBUG: Tables of loaded providers
...
```

core/src/main/java/org/fao/geonet/util/MailUtil.java

@@ -364,9 +364,6 @@ private static void configureBasics(String hostName, Integer smtpPort,
             email.setAuthenticator(new DefaultAuthenticator(username, password));
         }
 
-
-        email.setDebug(true);
-
         if (tls != null && tls) {
             email.setStartTLSEnabled(tls);
             email.setStartTLSRequired(tls);