chore!: reduce platform max block gas

[shumkov]

Issue being fixed or feature implemented

With the current max block size, the block contains about 1700 simple document batch transitions that make block execution pretty slow (up to 30 seconds), which in turn affects insertion time badly (UX).

What was done?

• Reduced block max gas by three times.

How Has This Been Tested?

None

Breaking Changes

The genesis consensus param is changed. Previously created networks won't be compatible.

Checklist:

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

For repository code-owners and collaborators only

• [x] I have assigned this pull request to a milestone