Auto_delete: Use last_action instead of last_recv

[jacobbaungard]

During node_disconnect last_recv of a node is reset. This has caused an issue where healthy nodes were deleted pre-maturely (for example if the auto_delete function ran during a config save on the remote node).

With this commit we:

• Use last_action instead which is not reset when nodes are disconnected
• Use time_t so we use consistent types
• If IPC is not connected we don't do anything

This fixes: MON-12562

Signed-off-by: Jacob Hansen jhansen@op5.com