Remove flag that's no longer being used

[davissp14]

This was preventing the event handler from working properly.

2023-02-16T19:26:27Z app[9185956b425e83] lax [info]repmgrd  | flag provided but not defined: -new-node-id
2023-02-16T19:26:27Z app[9185956b425e83] lax [info]repmgrd  | Usage of /usr/local/bin/event_handler:
2023-02-16T19:26:27Z app[9185956b425e83] lax [info]repmgrd  |   -details string
2023-02-16T19:26:27Z app[9185956b425e83] lax [info]repmgrd  |     	details
2023-02-16T19:26:27Z app[9185956b425e83] lax [info]repmgrd  |   -event string
2023-02-16T19:26:27Z app[9185956b425e83] lax [info]repmgrd  |     	event type
2023-02-16T19:26:27Z app[9185956b425e83] lax [info]repmgrd  |   -node-id int
2023-02-16T19:26:27Z app[9185956b425e83] lax [info]repmgrd  |     	the node id
2023-02-16T19:26:27Z app[9185956b425e83] lax [info]repmgrd  |   -success string
2023-02-16T19:26:27Z app[9185956b425e83] lax [info]repmgrd  |     	success (1) failure (0)
2023-02-16T19:26:27Z app[9185956b425e83] lax [info]repmgrd  | [2023-02-16 19:26:27] [WARNING] unable to execute event notification command
2023-02-16T19:26:27Z app[9185956b425e83] lax [info]repmgrd  | [2023-02-16 19:26:27] [DETAIL] parsed event notification command was:
2023-02-16T19:26:27Z app[9185956b425e83] lax [info]repmgrd  |   /usr/local/bin/event_handler -node-id 1537531293 -event child_node_disconnect -success 1 -details "standby node \"fdaa:0:2e26:a7b:7d18:391b:2e60:2\" (ID: 332095990) has disconnected" -new-node-id ''