[Stack 8.19.20-SNAPSHOT] [network_traffic] Failing test daily: system test: cassandra-mixed-frame in network_traffic.cassandra

- Stack version: 8.19.20-SNAPSHOT
- Package: network_traffic
- Failing test: system test: cassandra-mixed-frame
- DataStream: cassandra
- Owners:
- @elastic/sec-linux-platform

Error:
```
could not add data stream config to policy: could not create package policy (req {"name":"network_traffic-cassandra-64523","description":"","namespace":"64523","policy_id":"43bce74c-4a26-4834-a69f-affa7d9e1622","package":{"name":"network_traffic","version":"1.34.2"},"inputs":{"network-packet":{"enabled":true,"vars":{"interface":"/tmp/service_logs/cassandra_mixed_frame.pcap"},"streams":{"network_traffic.amqp":{"enabled":false},"network_traffic.cassandra":{"enabled":true},"network_traffic.dhcpv4":{"enabled":false},"network_traffic.dns":{"enabled":false},"network_traffic.flow":{"enabled":false},"network_traffic.http":{"enabled":false},"network_traffic.icmp":{"enabled":false},"network_traffic.memcached":{"enabled":false},"network_traffic.mongodb":{"enabled":false},"network_traffic.mysql":{"enabled":false},"network_traffic.nfs":{"enabled":false},"network_traffic.pgsql":{"enabled":false},"network_traffic.redis":{"enabled":false},"network_traffic.sip":{"enabled":false},"network_traffic
```

First build failed: https://buildkite.com/elastic/integrations/builds/47075

Start with the network_traffic system test cassandra-mixed-frame and the first failed Buildkite run (47075); inspect how the Cassandra DataStream package policy is created for cassandra_mixed_frame.pcap. Done means the package policy is created successfully and the system test passes.

Written by the indexing model from the issue text.