When failing back to PHP GetText, module is not always selected

[TheWitness]

Describe the bug

When the default php-gettext module is compiled and installed, Cacti does not use it regardless of the specification on the settings page.

To Reproduce

Steps to reproduce the behavior:

1. Set the language processor to builtin/none

2. Be at PHP version 8.1.2 to see deprecation warnings

3. Do something in Cacti

4. See deprecation warnings

Expected behavior

Cacti should use the php-gettext handler if it's installed and no other gettext handler is specified.