* fix SSZ response for `produceBlindedBlock`
In `produceBlindedBlock`, we sent the `ForkedBlindedBeaconBlock` when
requested to reply in SSZ format. However, expected result is just the
inner `ForkyBlindedBeaconBlock` together with `eth-consensus-version`.
Note: We do not use SSZ format in our VC for this endpoint at this time,
which explains why we haven't noticed earlier.
* fix Altair/Phase0