perf: use estimated count on item table

(cherry picked from commit 958cc6f8f8)

erpnext/controllers/queries.py

@@ -220,7 +220,7 @@ def item_query(doctype, txt, searchfield, start, page_len, filters, as_dict=Fals
 			filters.pop("supplier", None)
 
 	description_cond = ""
-	if frappe.db.count(doctype, cache=True) < 50000:
+	if frappe.db.estimate_count(doctype) < 50000:
 		# scan description only if items are less than 50000
 		description_cond = "or tabItem.description LIKE %(txt)s"
 

erpnext/stock/doctype/inventory_dimension/test_inventory_dimension.py

@@ -153,7 +153,6 @@ class TestInventoryDimension(FrappeTestCase):
 
 	def test_inventory_dimension_for_purchase_receipt_and_delivery_note(self):
 		frappe.clear_cache(doctype="Inventory Dimension")
-		frappe.clear_cache("Inventory Dimension")
 
 		inv_dimension = create_inventory_dimension(
 			reference_document="Rack", dimension_name="Rack", apply_to_all_doctypes=1