Bug 41580: (QA follow-up) Fix variable name mismatch in batch delete records

- The tidy declared const record_type but the code references
  recordtype (no underscore), causing a ReferenceError
- Rename to match the existing usage

To test:
- Go to Tools → Batch delete records
- Upload/select bibliographic records with checked out items
- Verify the red cross and yellow highlight appear for
  non-deletable records

Signed-off-by: Paul Derscheid <paul.derscheid@lmscloud.de>
Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>

koha-tmpl/intranet-tmpl/prog/en/modules/tools/batch_delete_records.tt

@@ -264,7 +264,7 @@
 [% MACRO jsinclude BLOCK %]
     [% INCLUDE 'datatables.inc' %]
     <script>
-        const record_type = "[% recordtype | html %]";
+        const recordtype = "[% recordtype | html %]";
     </script>
     <script>
         var MSG_CANNOT_BE_DELETED = _("This record cannot be deleted, at least one item is currently checked out.");