feat(db): added indexes related to sync

[andreabadesso]

Acceptance Criteria

• We must implement the indexes documented in https://github.com/HathorNetwork/internal-issues/issues/518
• We must check if the indexes already exist, because we've created them manually in mainnet and mainnet-staging

Checklist

• If you are requesting a merge into master, confirm this code is production-ready and can be included in future releases as soon as it gets merged
• Make sure either the unit tests and/or the QA tests are capable of testing the new features
• Make sure you do not include new dependencies in the project unless strictly necessary and do not include dev-dependencies as production ones. More dependencies increase the possibility of one of them being hijacked and affecting us.