Add redirection entries for Azure backup articles

Author: Saisang

.openpublishing.redirection.json

@@ -1,5 +1,20 @@
 {
   "redirections": [
+    {
+      "source_path": "articles/backup/backup-azure-enhanced-soft-delete-tutorial.md",
+      "redirect_url": "/azure/backup/secure-by-default",
+      "redirect_document_id": false
+    },
+    {
+      "source_path": "articles/backup/backup-azure-security-feature-cloud.md",
+      "redirect_url": "/azure/backup/secure-by-default",
+      "redirect_document_id": false
+    },
+    {
+      "source_path": "articles/backup/quick-backup-azure-enable-enhanced-soft-delete.md",
+      "redirect_url": "/azure/backup/secure-by-default",
+      "redirect_document_id": false
+    },
     {
       "source_path": "articles/azure-functions/functions-proxies.md",
       "redirect_url": "/previous-versions/azure/azure-functions/functions-proxies",