[conntrack]: Add Flag for unknown TCP connection direction when SYN is missed

[SRodi]

Background

TCP connections that existed before the deployment of Retina are currently subjected to a best-effort approach by conntrack to determine their direction. This method depends on the ACK flag on the TCP packet, which can be prone to errors due to the unpredictable nature of network traffic.

Goal

Create a flag in conntrack map to identify connections for which direction cannot be established for certain.

This will allow us to analyze the volume of affected connections. We can include this data in the heartbeat telemetry to monitor the issue over time and understand how the volume of affected connections changes.