[LogsDB] [Stack 8.19.21-SNAPSHOT] [zeek] Failing test daily: system test: logs in zeek.known_certs

- Stack version: 8.19.21-SNAPSHOT
- LogsDB: enabled
- Package: zeek
- Failing test: system test: logs
- DataStream: known_certs
- Owners:
- @elastic/integration-experience

Error:
```
could not assign policy to agent: error occurred while waiting for the policy to be assigned to all agents: can't get the agent: could not list agents: could not send request to Kibana API: Get "https://127.0.0.1:5601/api/fleet/agents/ed55d86b-a4cb-41b5-b9f8-c840db412676": context deadline exceeded
```

First build failed: https://buildkite.com/elastic/integrations/builds/49335

Start with Buildkite build 49335 and reproduce the failing system test: logs for the zeek known_certs data stream. Trace the policy-assignment timeout while requesting the Kibana Fleet agent, then determine whether the test passes reliably without the context deadline error.

Written by the indexing model from the issue text.