Extreme memory consumption in stork-server

Describe the bug Certain complicated large configurations with many subnets and shared-networks in Kea cause stork-server to consume extreme amounts of memory. This may require at least two Kea servers with such complex configurations before the memory consumption is triggered.

To Reproduce Steps to reproduce the behavior:

1. At least two kea-dhcp4 servers with 8169 subnets spread amongst 4455 shared-networks.
2. stork-agent 1.19.0 on each of the aforementioned Kea servers
3. A third server which houses the stork-server (though this could coexist on one of the other servers I suppose)
4. Start all Kea and stork services.
5. Register both stork-agent services in the stork-server.
6. With 32GB RAM in the server which houses stork-server, the process will consume all available memory over a relatively short period of time before being killed by OOM killer.
7. The process will continuously repeat.

Expected behavior No extreme memory usage

Environment:

• Kea version: This was tested with 2.6.1
• Stork: This was tested with 1.19.0
• OS: All three servers were running Debian 12 in Virtual Box VMs.
• Kea: ISC packages from Cloudsmith were used.
• Kea: Hooks are not necessary to trigger this.

RT24005