Remove fork designation and fork guard aliases

Remove fork designation and fork guard aliases

https://github.com/ChainSafe/lodestar/blob/734705659d0759f965935a36cf4854fc45d89697/packages/params/src/forkName.ts#L97-L101

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Changes below have been implemented by https://github.com/ChainSafe/lodestar/pull/7441

Somehing we should consider for the 2.0 release is to rename pre / post fork types as current semantics are confusing and require feature awareness of each fork instead of just knowing about the fork name itself, and order of forks, which is simple since it's alphabetical.

e.g.

`ForkPreBlobs` --> `ForkPreDeneb`

`ForkBlobs` --> `ForkPostDeneb`

`isForkBlobs` --> `isForkPostDeneb`

etc.

see https://github.com/ChainSafe/lodestar/blob/unstable/packages/params/src/forkName.ts