deprecate phase 0-only versions of beacon_blocks_by_{range,root}

[tersec]

There haven't been any phase0 blocks in mainnet or any of the still-supported testnets in MIN_EPOCHS_FOR_BLOCK_REQUESTS regardless, so the spec already technically supports not serving said blocks.

https://github.com/ethereum/consensus-specs/blob/dev/specs/altair/p2p-interface.md#beaconblocksbyrange-v2 and https://github.com/ethereum/consensus-specs/blob/dev/specs/altair/p2p-interface.md#beaconblocksbyroot-v2 work across all supported forks, including phase 0, and any CL client supporting Altair or newer already has to support those messages, so this maintains req/resp compatibility for phase 0 blocks.