Update serai-runtime to compile a minimum subset of itself for non-WASM targets

We only really care about it as a WASM blob, given `serai-abi`, so there's no
need to compile it twice when it's an expensive blob and we don't care about it
at all.

substrate/node/src/rpc/blockchain.rs

@@ -10,7 +10,6 @@ use sp_api::ProvideRuntimeApi;
 use sc_client_api::BlockBackend;
 
 use serai_abi::{primitives::prelude::*, SubstrateBlock as Block};
-use serai_runtime::*;
 
 use jsonrpsee::RpcModule;