`cdds_extract` Simulation mode not functioning as expected

Low priority:
When running `cdds_extract` on `request_cmip7_all.cfg` with `simulation = True`, it doesn't seem to be working quite right:

```
CRITICAL: archive data exists check FAILED for dataset moose:/crum/u-du152/ap4.pp (error_code: 0)
SIMULATED
CRITICAL: archive data exists check FAILED for dataset moose:/crum/u-du152/ap4.pp (error_code: 0)
SIMULATED
Stream ap4 completed ---------------- [1 of 1]

failed:
-- EXTRACT process exit:
-- script end --
-- EXTRACT process exit:
-- script end --
1
```
This issue would be to investigate and fix

Reproduce the issue by running `cdds_extract` with `request_cmip7_all.cfg` and `simulation = True`, then trace the simulation-mode handling around the archive data existence check. Confirm the expected simulated result and ensure the command does not end with the shown failure and exit status.

Written by the indexing model from the issue text.