Kusama not connecting to latest JSON RPC Specs on recent runtime upgrade

[rossbulat]

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Description of bug

Connections to the latest JSON RPC spec on Kusama are failing - both via RPC and smoldot. This is preventing Dapps from connecting to Kusama.

JSON RPC in question: https://paritytech.github.io/json-rpc-interface-spec/introduction.html

Thang @ Dedot debugging the issue: When Dedot calls chainHead_v1_follow, it always reject with a stop event

Basti suspects: This is because of the huge finality gap.

Stop event:

The stop event indicates that the JSON-RPC server was unable to provide a consistent list of the blocks at the head of the chain. This can happen because too many blocks have been pinned, because doing so would use an unreasonable amount of memory, or because a consensus mechanism creates a gap in the chain.

Steps to reproduce

This is being experienced application side. Please try connecting to Kusama on staking.polkadot.cloud as an example, where connections are hanging at connecting status.

[bkchr]

Probably related to the huge finality lag on Kusama. Maybe we should do some best effort in this situation and only return heads from the tip of the chain.

CC @lexnv