[chore] Cleanup code

[RogerKSI]

Implementation details

• remove unused code
• add mock gen command
• add chain_id in benchmark test
• add group module script for testing
• add account in genesis testing file
• adjust voting_period in genesis testing file

Please ensure the following requirements are met before submitting a pull request:

• The pull request is targeted against the correct target branch
• The pull request is linked to an issue with appropriate discussion and an accepted design OR is linked to a spec that describes the work.
• The pull request includes a description of the implementation/work done in detail.
• The pull request includes any and all appropriate unit/integration tests
• You have added a relevant changelog entry to CHANGELOG_UNRELEASED.md
• You have re-reviewed the files affected by the pull request (e.g. using the Files changed tab in the Github PR explorer)