Fix template path for reset functionality

- Update template_path to use relative path from class file
- Fix REVENIR AU MODELE OFFICIEL button functionality
- Ensure template detection works correctly
- Resolve template path mismatch issue

core/class/declarationtva_pdf.class.php

@@ -91,7 +91,7 @@ class DeclarationTVA_PDF
     {
         $this->db = $db;
         $this->entity = (int) $conf->entity;
-        $this->template_path = DOL_DOCUMENT_ROOT.'/custom/declarationtva/templates/declarationtva/';
+        $this->template_path = dirname(__FILE__) . '/../../templates/declarationtva/';
     }
 
     /**