fix: Alert message and make sure invoice due dates are different for effective test

- Make invoice due dates are different so that the invoice with the earliest due date is allocated first in the test
- Translate voucher type, simplify alert message. The invoice could be "split" into 1 row, no. of rows in the message seems unnecessary.

erpnext/accounts/doctype/payment_entry/payment_entry.py

@@ -1713,8 +1713,8 @@ def split_invoices_based_on_payment_terms(outstanding_invoices, company) -> list
 					continue
 
 				frappe.msgprint(
-					_("Spliting {} {} into {} row(s) as per Payment Terms").format(
-						split_rows[0]["voucher_type"], split_rows[0]["voucher_no"], len(split_rows)
+					_("Splitting {0} {1} as per Payment Terms").format(
+						_(entry.voucher_type), frappe.bold(entry.voucher_no)
 					),
 					alert=True,
 				)

erpnext/accounts/doctype/payment_entry/test_payment_entry.py

@@ -1270,7 +1270,10 @@ class TestPaymentEntry(FrappeTestCase):
 		customer = create_customer("Max Mustermann", "INR")
 		create_payment_terms_template()
 
-		si = create_sales_invoice(qty=1, rate=100, customer=customer)
+		# SI has an earlier due date and SI2 has a later due date
+		si = create_sales_invoice(
+			qty=1, rate=100, customer=customer, posting_date=add_days(nowdate(), -4)
+		)
 		si2 = create_sales_invoice(do_not_save=1, qty=1, rate=100, customer=customer)
 		si2.payment_terms_template = "Test Receivable Template"
 		si2.submit()
@@ -1286,8 +1289,8 @@ class TestPaymentEntry(FrappeTestCase):
 		args.update(
 			{
 				"get_outstanding_invoices": True,
-				"from_posting_date": nowdate(),
-				"to_posting_date": add_days(nowdate(), 7),
+				"from_posting_date": add_days(nowdate(), -4),
+				"to_posting_date": add_days(nowdate(), 2),
 			}
 		)
 		references = get_outstanding_reference_documents(args)