[INFERENCE] Node ID and Heartbeart Bugfix

[samherring99]

This PR fixes two bugs found in testing:

1. The node ID that is logged on discovery is never cleared / reset, leading to failing requests when an inference node drops and rejoins. This PR adds a removal mechanism after 2 missed heartbeats to avoid routing requests to stale nodes.
2. The heartbeat mechanism sends gossip messages with the same message hash, so they aren't received by the gateway. This change adds a timestamp to the gossip message for uniqueness and ensures each heartbeat is received.

Tested on hgx-2.