cosmos-sdk --grpc-only is not integrated in start cmd

[yihuang]

Proposal: Integrate --grpc-only flag in start cmd

Current behavior: don't support grpc only mode

Desired behavior: [What you would like to happen]

Use case: [Why is this important (helps with prioritizing requests)]

Requests may be closed if we're not actively planning to work on them.

[fedekunze]

what's the problem context for this?

[VictorTrustyDev]

This is the purpose of the --grpc-only flag: cosmos-sdk#10796

[VictorTrustyDev]

Perhaps he doesn't want new upgrades effect the historical data querying process.

Like this #1242, the new module make we unable to call old blocks due to nil params.

[yihuang]

what's the problem context for this?

Other than the use case in original cosmos-sdk PR, we are doing a feature of distributed query service by replicating the chain state directly, which should be less costly than just running multiple full nodes. In this setup, it only have one full node and multiple read-only replicates which serve grpc queries only.
It helps with offloading the most heavy parts of the json-rpc apis to this distributed query service: traceTransaction, ethCall, estimateGas