create-testnet-data: fix generation of Conway genesis w.r.t. delegation of voting power

[smelc]

Changelog

- description: |
    Fix that the `initialDReps` fields in the `conway-genesis.json` file generated by `create-testnet-data` was incomplete.
# uncomment types applicable to the change:
  type:
  # - feature        # introduces a new feature
  # - breaking       # the API has changed in a breaking way
  # - compatible     # the API has changed but is non-breaking
  # - optimisation   # measurable performance improvements
  # - refactoring    # QoL changes
  - bugfix         # fixes a defect
  - test           # fixes/modifies tests
  # - maintenance    # not directly related to the code
  # - release        # related to a new release preparation
  # - documentation  # change in code docs, haddocks...

Context

While testing #911, I noticed that the SPO created by create-testnet-data doesn't delegate its voting power to a DRep.

So I looked at create-testnet-data and found that only the --stake-delegators created by create-testnet-data delegate to DReps (whereas the SPO is created by --pools). But then, starting with --stake-delegators, there is a bug (introduced in https://github.com/IntersectMBO/cardano-cli/pull/940/files#diff-46f6afb73150af450b10d232ebdca10061efd5a69e268f5b0870439aca3b19e0) that causes an incorrect conway-genesis to be created.

This PR fixes that

How to trust this PR

TBD

Checklist

• Commit sequence broadly makes sense and commits have useful messages
• New tests are added if needed and existing tests are updated. See Running tests for more details
• Self-reviewed the diff

[smelc]

This PR is useless, by virtue of the explanation here: IntersectMBO/cardano-ledger#4782 (comment)

This PR was causing the following change:

But it is not required, because, as @lehins explained; the field delegators is derived from delegs; so we don't need to populate it. I'll do another PR to add some comments to the code, so that we keep a trace of this, because this is confusing IMO.