fix: pos invoice consolidation row refer issue (backport #48057) (#48058)

fix: pos invoice consolidation row refer issue (#48057)

(cherry picked from commit 4178d9e2a1)

Co-authored-by: Diptanil Saha <diptanil@frappe.io>

erpnext/accounts/doctype/pos_invoice_merge_log/pos_invoice_merge_log.py

@@ -258,6 +258,7 @@ class POSInvoiceMergeLog(Document):
 				if not found:
 					tax.charge_type = "Actual"
 					tax.idx = idx
+					tax.row_id = None
 					idx += 1
 					tax.included_in_print_rate = 0
 					tax.tax_amount = tax.tax_amount_after_discount_amount