test: fix flaky purchase receipt test (#26859)

erpnext/stock/doctype/purchase_receipt/test_purchase_receipt.py

@@ -324,21 +324,8 @@ class TestPurchaseReceipt(unittest.TestCase):
 
 		pr1.submit()
 		self.assertRaises(frappe.ValidationError, pr2.submit)
+		frappe.db.rollback()
 
-		pr1.cancel()
-		se.cancel()
-		se1.cancel()
-		se2.cancel()
-		se3.cancel()
-		po.reload()
-		pr2.load_from_db()
-
-		if pr2.docstatus == 1 and frappe.db.get_value('Stock Ledger Entry',
-			{'voucher_no': pr2.name, 'is_cancelled': 0}, 'name'):
-			pr2.cancel()
-
-			po.load_from_db()
-			po.cancel()
 
 	def test_serial_no_supplier(self):
 		pr = make_purchase_receipt(item_code="_Test Serialized Item With Series", qty=1)