Remove Client::clone_with. (#3747)

## Motivation

`Client::clone_with` creates a clone with a different set of tracked
chains. This is used when downloading a new chain's parent chain. But
it's not actually necessary, since we want to track the new chain
anyway, and it suffices to track the child, not the parent, to make sure
the `OpenChain` message is handled.

## Proposal

Remove `clone_with`; directly add the child to the tracked chains.

## Test Plan

CI

## Release Plan

- Nothing to do / These changes follow the usual release cycle.

## Links

- [reviewer
checklist](https://github.com/linera-io/linera-protocol/blob/main/CONTRIBUTING.md#reviewer-checklist)

Author: afck

linera-client/src/client_context.rs

@@ -402,12 +402,7 @@ where
         S: Storage + Clone + Send + Sync + 'static,
     {
         let node_provider = self.make_node_provider();
-        let client = self.client.clone_with(
-            node_provider.clone(),
-            "Temporary client for fetching the parent chain",
-            vec![message_id.chain_id, chain_id],
-            false,
-        );
+        self.client.track_chain(chain_id);
 
         // Take the latest committee we know of.
         let admin_chain_id = self.wallet.genesis_admin_chain();
@@ -418,7 +413,11 @@ where
                 .map(|(public_key, node)| RemoteNode { public_key, node })
                 .collect()
         } else {
-            let info = client.local_node().handle_chain_info_query(query).await?;
+            let info = self
+                .client
+                .local_node()
+                .handle_chain_info_query(query)
+                .await?;
             let committee = info
                 .latest_committee()
                 .ok_or(error::Inner::ChainInfoResponseMissingCommittee)?;
@@ -430,13 +429,14 @@ where
 
         // Download the parent chain.
         let target_height = message_id.height.try_add_one()?;
-        client
+        self.client
             .download_certificates(&nodes, message_id.chain_id, target_height)
             .await
             .context("downloading parent chain")?;
 
         // The initial timestamp for the new chain is taken from the block with the message.
-        let certificate = client
+        let certificate = self
+            .client
             .local_node()
             .certificate_for(&message_id)
             .await

linera-core/src/client/mod.rs

@@ -221,41 +221,6 @@ impl<P, S: Storage + Clone> Client<P, S> {
         }
     }
 
-    /// Returns a clone with a different set of tracked chains.
-    pub fn clone_with(
-        &self,
-        validator_node_provider: P,
-        name: impl Into<String>,
-        tracked_chains: impl IntoIterator<Item = ChainId>,
-        long_lived_services: bool,
-    ) -> Self {
-        let tracked_chains = Arc::new(RwLock::new(tracked_chains.into_iter().collect()));
-        let state = WorkerState::new_for_client(
-            name.into(),
-            self.storage.clone(),
-            tracked_chains.clone(),
-            self.max_loaded_chains,
-        )
-        .with_long_lived_services(long_lived_services)
-        .with_allow_inactive_chains(true)
-        .with_allow_messages_from_deprecated_epochs(true);
-        let local_node = LocalNodeClient::new(state);
-        Self {
-            validator_node_provider,
-            local_node,
-            chains: DashMap::new(),
-            max_pending_message_bundles: self.max_pending_message_bundles,
-            message_policy: MessagePolicy::new(BlanketMessagePolicy::Accept, None),
-            cross_chain_message_delivery: self.cross_chain_message_delivery,
-            grace_period: self.grace_period,
-            tracked_chains,
-            notifier: Arc::new(ChannelNotifier::default()),
-            storage: self.storage.clone(),
-            max_loaded_chains: self.max_loaded_chains,
-            blob_download_timeout: self.blob_download_timeout,
-        }
-    }
-
     /// Returns the storage client used by this client's local node.
     #[instrument(level = "trace", skip(self))]
     pub fn storage_client(&self) -> &S {