[Subscription basic] [zeek] Failing test daily: system test: logs in zeek.ftp

- Stack version: Same as in Pull Request builds
- Subscription: basic
- Package: zeek
- Failing test: system test: logs
- DataStream: ftp
- Owners:
- @elastic/integration-experience

Error:
```
could not assign policy to agent: error occurred while waiting for the policy to be assigned to all agents: timeout: policy hasn't been assigned in time
```

First build failed: https://buildkite.com/elastic/integrations/builds/45020

Start with the failing `system test: logs` for the `zeek.ftp` DataStream and compare it with Buildkite build 45020. Investigate the policy-assignment timeout during the test run; done means the test completes reliably without the agent policy timeout.

Written by the indexing model from the issue text.