Describe the feature

we stopped using total difficulty a while ago and require that all difficulty activated hardforks (merge) are known and completed.

we currently still maintain the total difficulty table, which is effectively unused now.
so we can drop support for:

and all read/writes/unwinds etc.
we should entirely stop using this.

however there could be some edge cases when a user downgrades, so this changes must be done with this in mind

Additional context

No response