fix(en): run MainNodeFeeParamsFetcher in API component (#1988)

## What ❔

Runs `MainNodeFeeParamsFetcher` in `run_api`.
Removes it from `run_core`.

## Why ❔

En's core doesn't use `MainNodeFeeParamsFetcher`. API uses it. API
operated normally only if Core and Api are launched in the same process
which is not true for distributed nodes. The PR fixes it

## Checklist

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- [ ] PR title corresponds to the body of PR (we generate changelog
entries from PRs).
- [ ] Tests for the changes have been added / updated.
- [ ] Documentation comments have been added / updated.
- [ ] Code has been formatted via `zk fmt` and `zk lint`.
- [ ] Spellcheck has been run via `zk spellcheck`.

core/bin/external_node/src/main.rs

@@ -206,7 +206,6 @@ async fn run_core(
     task_handles: &mut Vec<JoinHandle<anyhow::Result<()>>>,
     app_health: &AppHealthCheck,
     stop_receiver: watch::Receiver<bool>,
-    fee_params_fetcher: Arc<MainNodeFeeParamsFetcher>,
     singleton_pool_builder: &ConnectionPoolBuilder<Core>,
 ) -> anyhow::Result<SyncState> {
     // Create components.
@@ -311,8 +310,6 @@ async fn run_core(
     }
 
     let sk_handle = task::spawn(state_keeper.run());
-    let fee_params_fetcher_handle =
-        tokio::spawn(fee_params_fetcher.clone().run(stop_receiver.clone()));
     let remote_diamond_proxy_addr = config.remote.diamond_proxy_addr;
     let diamond_proxy_addr = if let Some(addr) = config.optional.contracts_diamond_proxy_addr {
         anyhow::ensure!(
@@ -377,7 +374,6 @@ async fn run_core(
 
     task_handles.extend([
         sk_handle,
-        fee_params_fetcher_handle,
         consistency_checker_handle,
         commitment_generator_handle,
         updater_handle,
@@ -432,6 +428,10 @@ async fn run_api(
         stop_receiver.clone(),
     )));
 
+    let fee_params_fetcher_handle =
+        tokio::spawn(fee_params_fetcher.clone().run(stop_receiver.clone()));
+    task_handles.push(fee_params_fetcher_handle);
+
     let tx_sender_builder =
         TxSenderBuilder::new(config.into(), connection_pool.clone(), Arc::new(tx_proxy));
 
@@ -632,8 +632,6 @@ async fn init_tasks(
         task_handles.push(tokio::spawn(fetcher.run(stop_receiver.clone())));
     }
 
-    let fee_params_fetcher = Arc::new(MainNodeFeeParamsFetcher::new(main_node_client.clone()));
-
     let sync_state = if components.contains(&Component::Core) {
         run_core(
             config,
@@ -643,7 +641,6 @@ async fn init_tasks(
             task_handles,
             app_health,
             stop_receiver.clone(),
-            fee_params_fetcher.clone(),
             &singleton_pool_builder,
         )
         .await?
@@ -660,6 +657,7 @@ async fn init_tasks(
     };
 
     if components.contains(&Component::HttpApi) || components.contains(&Component::WsApi) {
+        let fee_params_fetcher = Arc::new(MainNodeFeeParamsFetcher::new(main_node_client.clone()));
         run_api(
             task_handles,
             config,