Explicitly forbid dependencies for scenarios with DSE jobs

[amaslenn]

Summary

Provide a concise summary of the changes introduced by this pull request. Detail the purpose and scope of the changes, referencing any relevant issues or discussions. Explain how these changes address the problem or improve the project.

Fixes internal bug.

Test Plan

1. CI (extended).
2. Run dry-run using configs from the bug:

...
[INFO] System Name: example-cluster
[INFO] Scheduler: slurm
[INFO] Test Scenario Name: ncclint-test
[INFO] Checking if workloads components are installed.
[INFO] Test Scenario: ncclint-test

Section Name: Tests.all_reduce
  Test Name: ncclint_base_test
  Description: NCCL internal plugin base test configuration
  No dependencies
Section Name: Tests.reduce_scatter
  Test Name: ncclint_base_test
  Description: NCCL internal plugin base test configuration
  Start Post Comp: Tests.all_reduce
Section Name: Tests.all_gather
  Test Name: ncclint_base_test
  Description: NCCL internal plugin base test configuration
  Start Post Comp: Tests.reduce_scatter
[INFO] Initializing Runner [DRY-RUN] mode
[INFO] Creating SlurmRunner
[ERROR] Dependencies are not supported for DSE jobs, all cases run consecutively. Please remove dependencies and re-run.

Additional Notes

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