SDP-341: harden recreate_db_checkpoint.sh and recreate_db_sync_replica.sh save-dir cleanup.
Capture the save directory by resolved real path BEFORE switch_db_files swaps the root/offline_db symlinks, then delete via that fixed path instead of re-resolving the swapped OFFLINE_DB/P4ROOT symlinks (which on shared storage can point at another node's live data). recreate_db_checkpoint.sh now passes sdp_health_check SDP-341 known-safe marker; verified end-to-end (full offline_db<->root cutover, data intact, checkpoint produced).