Blob sidecars deprecated on Fusaka

Due to the Peer-DAS changes merged on Fusaka, blob sidecars are no longer relevant and clients will stop supporting them (see [https://github.com/ethereum/beacon-APIs/pull/546](https://github.com/ethereum/beacon-APIs/pull/546)). To get info from blobs, goteth will have to fetch them through `/eth/v1/beacon/blobs/{block_id}` and see if its worth computing the extra fields that sidecars has. 