Revert "subxt: Use unstable backend for light client"

This reverts commit ea6f3cc58b.

subxt/Cargo.toml

@@ -61,7 +61,7 @@ unstable-metadata = []
 
 # Activate this to expose the Light Client functionality.
 # Note that this feature is experimental and things may break or not work as expected.
-unstable-light-client = ["subxt-lightclient", "tokio-stream", "tokio"]
+unstable-light-client = ["subxt-lightclient", "tokio-stream"]
 
 [dependencies]
 async-trait = { workspace = true }
@@ -117,7 +117,6 @@ getrandom = { workspace = true, optional = true }
 
 # Included if "native" feature is enabled
 tokio-util = { workspace = true, features = ["compat"], optional = true }
-tokio = { workspace = true, features = ["macros", "time", "rt-multi-thread"], optional = true }
 
 [dev-dependencies]
 bitvec = { workspace = true }

subxt/src/client/light_client/mod.rs

@@ -93,29 +93,7 @@ impl RawLightClient {
     ) -> Result<LightClient<TChainConfig>, crate::Error> {
         let raw_rpc = self.raw_rpc.for_chain(chain_id);
         let rpc_client = RpcClient::new(raw_rpc.clone());
-
-        use crate::backend::unstable::UnstableBackend;
-        use std::sync::Arc;
-        let (backend, mut driver) = UnstableBackend::builder().build(rpc_client);
-        let future = async move {
-            use futures::StreamExt;
-            while let Some(val) = driver.next().await {
-                if let Err(e) = val {
-                    // This is a test; bail if something does wrong and try to
-                    // ensure that the message makes it to some logs.
-                    eprintln!("Error driving unstable backend in tests (will panic): {e}");
-                    panic!("Error driving unstable backend in tests: {e}");
-                }
-            }
-        };
-        // The unstable backend needs driving:
-        #[cfg(feature = "native")]
-        tokio::spawn(future);
-        #[cfg(feature = "web")]
-        wasm_bindgen_futures::spawn_local(future);
-        let client = OnlineClient::from_backend(Arc::new(backend))
-            .await
-            .map_err(|e| format!("Cannot construct OnlineClient from backend: {e}"))?;
+        let client = OnlineClient::<TChainConfig>::from_rpc_client(rpc_client).await?;
 
         Ok(LightClient { client, chain_id })
     }