Header.BaseFee is set to non-zero for london fork disabled

[begmaroman]

Description

Return zero basefee if the london hardfork is disabled

Changes include

• Bugfix (non-breaking change that solves an issue)
• Hotfix (change that solves an urgent issue, and requires immediate attention)
• New feature (non-breaking change that adds functionality)
• Breaking change (change that is not backwards-compatible and/or changes current functionality)

Checklist

• I have assigned this PR to myself
• I have added at least 1 reviewer
• I have added the relevant labels
• I have updated the official documentation
• I have added sufficient documentation in code

Testing

• I have tested this code with the official test suite
• I have tested this code manually

[begmaroman]

Tested manually. Sent several transactions with disabled london hardfork via Metamask.

[Nemanja0x]

One thing to remember, maybe I'll create a ticket. If we have london fork disabled and we enable it at block 100: It can happen that a node which is started after block 100 has different hash of genesis block. This is because genesis header will use the new configuration where the baseFee is not 0. Nevertheless, if this is assumption is correct, it is a new bug. The one reported here is solved.