(fix): agent-builder to include workflow execution output after lazy-load I/O change

[rosomri]

Summary

Fixes workflow execution output retrieval for agent-builder consumers.

After #253547 changed getWorkflowExecution to exclude step I/O by default, getExecutionState was no longer receiving step outputs - causing getWorkflowOutput to always return null.

This passes includeOutput: true explicitly so the output is available when the execution completes.

[elasticmachine]

💛 Build succeeded, but was flaky

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• Commit: db31d0e

Failed CI Steps

• FTR Configs #69

Test Failures

• [job] [logs] FTR Configs #69 / Journey[web_logs_dashboard_long_running] Return to dashboard

Metrics [docs]

✅ unchanged