chore: activate platform on EHF fork

[shumkov]

Issue being fixed or feature implemented

Drive is using v20 fork to activate Platform but must be mn_rr (EHF).
Dashmate is using initial core chain locked height. We want to use EHF fork to use fork activation.

What was done?

• Used mn_rr instead of v20 in Drive
• Activate EHF spork in dashmate and remove initial core chain locked height

How Has This Been Tested?

Running local network

Breaking Changes

None

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