perf: Drop cost center index

This was only added to allow renaming for one user (?) can be added if
there's a more serious use case than that.

erpnext/accounts/doctype/gl_entry/gl_entry.json

@@ -104,8 +104,7 @@
    "label": "Cost Center",
    "oldfieldname": "cost_center",
    "oldfieldtype": "Link",
-   "options": "Cost Center",
-   "search_index": 1
+   "options": "Cost Center"
   },
   {
    "fieldname": "debit",
@@ -357,7 +356,7 @@
  "idx": 1,
  "in_create": 1,
  "links": [],
- "modified": "2025-04-21 22:10:25.844576",
+ "modified": "2025-04-21 22:37:16.349564",
  "modified_by": "Administrator",
  "module": "Accounts",
  "name": "GL Entry",