perf: cache journal entry balances for 5 minutes

If user is repeatedly adding multiple JV lines then everytime the value
will be refetched from database, reading GLE table can be very expensive
on large DBs.

AFAIK this function is only for UX and balances are anyways overidden
when saving the document.

Proper fix: maybe use closing balance here?

erpnext/accounts/doctype/journal_entry/journal_entry.py

@@ -7,6 +7,7 @@ import json
 import frappe
 from frappe import _, msgprint, scrub
 from frappe.utils import cstr, flt, fmt_money, formatdate, get_link_to_form, nowdate
+from frappe.utils.caching import redis_cache
 
 import erpnext
 from erpnext.accounts.deferred_revenue import get_deferred_booking_accounts
@@ -1478,6 +1479,7 @@ def get_outstanding(args):
 
 
 @frappe.whitelist()
+@redis_cache(ttl=5 * 60, user=True)
 def get_party_account_and_balance(company, party_type, party, cost_center=None):
 	if not frappe.has_permission("Account"):
 		frappe.msgprint(_("No Permission"), raise_exception=1)