[frr-10.0.1] Debug code for route-map RM_SET_SRC missing

1. Print candidate-config and running-config in mgmt_txn_prepare_config
2. Print dnode xpath around dnode_create
3. Add mutex lock in lyd_new_path
4. Find dnode for xpath having RM_SET_SRC with value 10.1.0.32 and cache it,
   then check the same dnode in mgmt_txn_prepare_config