Reduce cost by preventing ethers.js `eth_chainId` calls

[juliangruber]

eth_chainId is one of our most expensive calls in total. Let's prevent it wherever we can.

@bajtos found a recipe:

https://github.com/ethers-io/ethers.js/blob/0195f440e35d11f84874f58d80b2071f52c4b17f/docs.wrm/migrating.wrm#L240-L244

Here are all repos instantiating Ethers.js:

• desktop
• spark-checker
• node
• spark-rewards
• spark-evaluate
• spark-api
• index-provider-peer-id
• spark-rewards
• spark-stats

[bajtos]

I think the services running on Fly.io and the test suites are spending very little CUs and most of the traffic comes from code running on Checker nodes.

I propose to implement the fix in the following repositories first:

• desktop
• node
• spark-checker