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/beacon_chain/src/blob_verification.rs

@@ -14,7 +14,7 @@ use crate::{metrics, BeaconChainError};
 use kzg::{Error as KzgError, Kzg, KzgCommitment};
 use ssz_derive::{Decode, Encode};
 use std::time::Duration;
-use tracing::debug;
+use tracing::{debug, instrument};
 use tree_hash::TreeHash;
 use types::blob_sidecar::BlobIdentifier;
 use types::{
@@ -374,6 +374,7 @@ impl<E: EthSpec> IntoIterator for KzgVerifiedBlobList<E> {
 ///
 /// Note: This function should be preferred over calling `verify_kzg_for_blob`
 /// in a loop since this function kzg verifies a list of blobs more efficiently.
+#[instrument(skip_all, level = "debug")]
 pub fn verify_kzg_for_blob_list<'a, E: EthSpec, I>(
     blob_iter: I,
     kzg: &'a Kzg,