Instrument tracing spans for block processing and import (#7816)

#7815

- removes all existing spans, so some span fields that appear in logs like `service_name` may be lost.
- instruments a few key code paths in the beacon node, starting from **root spans** named below:

* Gossip block and blobs
* `process_gossip_data_column_sidecar`
* `process_gossip_blob`
* `process_gossip_block`
* Rpc block and blobs
* `process_rpc_block`
* `process_rpc_blobs`
* `process_rpc_custody_columns`
* Rpc blocks (range and backfill)
* `process_chain_segment`
* `PendingComponents` lifecycle
* `pending_components`

To test locally:
* Run Grafana and Tempo with https://github.com/sigp/lighthouse-metrics/pull/57
* Run Lighthouse BN with `--telemetry-collector-url http://localhost:4317`

Some captured traces can be found here: https://hackmd.io/@jimmygchen/r1sLOxPPeg

Removing the old spans seem to have reduced the memory usage quite a lot - i think we were using them on long running tasks and too excessively:
<img width="910" height="495" alt="image" src="https://github.com/user-attachments/assets/5208bbe4-53b2-4ead-bc71-0b782c788669" />

beacon_node/network/src/sync/manager.rs

@@ -68,7 +68,7 @@ use std::ops::Sub;
 use std::sync::Arc;
 use std::time::Duration;
 use tokio::sync::mpsc;
-use tracing::{debug, error, info, info_span, trace, Instrument};
+use tracing::{debug, error, info, trace};
 use types::{
     BlobSidecar, DataColumnSidecar, EthSpec, ForkContext, Hash256, SignedBeaconBlock, Slot,
 };
@@ -263,14 +263,7 @@ pub fn spawn<T: BeaconChainTypes>(
 
     // spawn the sync manager thread
     debug!("Sync Manager started");
-    executor.spawn(
-        async move {
-            Box::pin(sync_manager.main())
-                .instrument(info_span!("", service = "sync"))
-                .await
-        },
-        "sync",
-    );
+    executor.spawn(async move { Box::pin(sync_manager.main()).await }, "sync");
 }
 
 impl<T: BeaconChainTypes> SyncManager<T> {