fix: undo Sonar vulnerability

apps/onboarding-functions/src/main/java/it/pagopa/selfcare/onboarding/service/ContractServiceDefault.java

@@ -284,28 +284,21 @@ private File createPdfFileContract(
 
   private File createPdfFileAttachment(String attachmentTemplatePath, Onboarding onboarding)
       throws IOException {
-    String timestamp = LocalDateTime.now().format(DateTimeFormatter.ofPattern("yyyyMMddHHmmss"));
-    String uniqueId = UUID.randomUUID().toString();
-    String filePrefix = "allegato_interoperabilita_" + timestamp + "_" + uniqueId;
-
-    // Usa una directory temporanea dedicata
-    Path tempDir = Files.createTempDirectory("secureTempDir");
-
-    // Crea il file temporaneo nella directory sicura
-    Path attachmentPdfFile = Files.createTempFile(tempDir, filePrefix, ".pdf");
+    final String builder =
+        LocalDateTime.now().format(DateTimeFormatter.ofPattern("yyyyMMddHHmmss"))
+            + "_"
+            + UUID.randomUUID()
+            + "_allegato_interoperabilita.";
 
-    // Leggi il contenuto del template del contratto
+    // Read the content of the contract template file.
     String attachmentTemplateText = azureBlobClient.getFileAsText(attachmentTemplatePath);
-
-    // Prepara i dati comuni per il documento PDF
+    // Create a temporary PDF file to store the contract.
+    Path attachmentPdfFile = Files.createTempFile(builder, ".pdf");
+    // Prepare common data for the contract document.
     Map<String, Object> data = setUpAttachmentData(onboarding);
 
     log.debug("data Map for PDF: {}", data);
-
-    // Scrivi i dati nel file PDF
     fillPDFAsFile(attachmentPdfFile, attachmentTemplateText, data);
-
-    // Restituisci il file temporaneo
     return attachmentPdfFile.toFile();
   }