chore: update testnet genesis and core nightly

[shumkov]

Issue being fixed or feature implemented

We need to align dashmate to recent testnet settings

What was done?

• Updated testnet genesis
• Updated Core to 20.1.0-nightly.2024.02.15

How Has This Been Tested?

None

Breaking Changes

Previous testnet was destroyed so there is no breaking change

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added or updated relevant unit/integration/functional/e2e tests
• I have added "!" to the title and described breaking changes in the corresponding section if my code contains any
• I have made corresponding changes to the documentation if needed

For repository code-owners and collaborators only

• I have assigned this pull request to a milestone