Add a validator that all `./flow_cleanup.sh` tasks have executed successfully.

The `flow_setup.sh` already does this. It will give out some kind of stat at the end of its execution where it indicates that all previous tasks have executed successfully.

```
OK: sr start was successful
Overall dynamic_flow: PASSED 4/4 checks passed!
```

Something like this would also be useful in the `flow_cleanup.sh` script.

Compare flow_cleanup.sh with flow_setup.sh, focusing on how flow_setup.sh reports successful task execution. Run flow_cleanup.sh and verify that it reports an overall success status and the number of successful checks, with failure reflected when a task does not succeed.

Written by the indexing model from the issue text.