Restore from TACACS backup if present, upon load-minigraph during upd…

…ate-graph action.

Equivalent to master change PR sonic-net#6285

files/image_config/updategraph/updategraph

@@ -1,6 +1,7 @@
 #!/bin/bash
 
 CONFIG_DB_INDEX=4
+TACACS_JSON_BACKUP=tacacs.json
 
 reload_minigraph()
 {
@@ -15,6 +16,11 @@ reload_minigraph()
  acl-loader update full /etc/sonic/acl.json
  fi
  config qos reload
+ if [ -r /etc/sonic/old_config/${TACACS_JSON_BACKUP} ]; then
+ sonic-cfggen -j /etc/sonic/old_config/${TACACS_JSON_BACKUP} --write-to-db
+ else
+ echo "Missing tacacs json to restore tacacs credentials"
+ fi
  DEVICE_TYPE=`sonic-cfggen -m -v DEVICE_METADATA.localhost.type`
  if [ "${DEVICE_TYPE}" != "MgmtToRRouter" ]; then
  pfcwd start_default