Delete `lighthouse/beacon/states/{state_id}/ssz` endpoint

[michaelsproul]

Description

lighthouse/beacon/states/{state_id}/ssz

This endpoint is redundant and no longer required, because equivalent endpoints now exist in the standard beacon API.

Version

Lighthouse v4.6.0-rc.0

[hoseincc]

Hi

[Doomersan]

Hello, may I be assigned to complete this one?
Is it just a matter of removing this function
and this line

[michaelsproul]

Sorry @Doomersan, already done here #5065