`web3call` provider validation on start

Do you want to request a feature or report a bug?
bug

What is the current behavior?
When provider of type web3call specified, graph-node doesn't validate it on start. So you can specify any non-existing URL and graph node will not notice it until the first eth_call call.

I guess the issue is that EthereumNetworks::flatten() method that's used for provider validation, omits call_only_adapters field

If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem.
Add a provider with non-existing url:
{ label = "calls", details = { type = "web3call", url = "http://asdf", features = [ "archive" ] }},

What is the expected behavior?
Should drop that provider on start.

chain/ethereum/src/network.rs、特に EthereumNetworks::flatten() から始め、provider の検証中に call_only_adapters がどのように扱われるかを調べてください。存在しない URL http://asdf を使用する web3call provider で問題を再現し、無効な provider が最初の eth_call の時点ではなく、起動中に削除されることを確認してください。