firehose: fix optimism check in extended blocks check

[YaroShkvorets]

Problem

provides_extended_blocks() matches on optimism-mainnet, while on Firehose endpoints by convention we are using optimism id from the Networks Registry. Same as in Graph Explorer and elsewhere in The Graph ecosystem.

❯ grpcurl optimism.firehose.pinax.network:443 sf.firehose.v2.EndpointInfo/Info
{
  "chainName": "optimism",
  "chainNameAliases": [
    "evm-10",
    "op-mainnet",
    "optimism-mainnet"
  ],
  "firstStreamableBlockId": "7ca38a1916c42007829c55e69d3e9a73265554b586a499015373241b8a3fa48b",
  "blockIdEncoding": "BLOCK_ID_ENCODING_HEX",
  "blockFeatures": [
    "hybrid",
    "extended@105235064"
  ]
}

❯ grpcurl -H "X-Api-Key: $SF_API_KEY" mainnet.optimism.streamingfast.io:443 sf.firehose.v2.EndpointInfo/Info
{
  "chainName": "optimism",
  "chainNameAliases": [
    "evm-10",
    "op-mainnet",
    "optimism-mainnet"
  ],
  "firstStreamableBlockId": "7ca38a1916c42007829c55e69d3e9a73265554b586a499015373241b8a3fa48b",
  "blockIdEncoding": "BLOCK_ID_ENCODING_HEX",
  "blockFeatures": [
    "hybrid",
    "extended@105235064"
  ]
}

This PR just changes the hardcoded value for Optimism but IMO the cleaner way would be to just check for starts_with("extended") without hardcoding Optimism and Arbitrum ONE chain names at all.

Can change to that if needed.