fix: avoid deleting peers on graceful close (#14165)

* fix: avoid deleting peers on graceful close

- Fixes an issue where a coordinator deletes all
  its peers on shutdown. This can cause disconnects
  whenever a coderd is redeployed.

coderd/database/queries/tailnet.sql

@@ -149,6 +149,14 @@ DO UPDATE SET
 	updated_at = now() at time zone 'utc'
 RETURNING *;
 
+-- name: UpdateTailnetPeerStatusByCoordinator :exec
+UPDATE 
+	tailnet_peers
+SET
+	status = $2
+WHERE
+	coordinator_id = $1;
+
 -- name: DeleteTailnetPeer :one
 DELETE
 FROM tailnet_peers