triggerdialog_rest_password and triggerdialog_masSecret get NULLed when I save anything in the configuration UI

[ekkeguembel]

Describe the bug
triggerdialog_rest_password and triggerdialog_masSecret get NULLed when I save anything in the configuration UI

To Reproduce
Steps to reproduce the behavior:

1. Start with a working installation, or create one by entering all data in configuration -> Print Mailing Settings
2. check the data in local.php
3. Now change anything in configuration -> Print Mailing Settings (e.g., for testing, change the REST API user name
4. As a result, we now have deleted the secrets in local.php
   'triggerdialog_masSecret' => null,
   'triggerdialog_rest_password' => null,

Expected behavior
secrets must not be displayed in the UI, but must remain intact in local.php

Mautic version
4

Additional context
Porbably related to #21