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" />

book/src/help_bn.md

@@ -392,6 +392,9 @@ Options:
           database.
       --target-peers <target-peers>
           The target number of peers.
+      --telemetry-collector-url <URL>
+          URL of the OpenTelemetry collector to export tracing spans (e.g.,
+          http://localhost:4317). If not set, tracing export is disabled.
       --trusted-peers <TRUSTED_PEERS>
           One or more comma-delimited trusted peer ids which always have the
           highest score according to the peer scoring system.

book/src/help_general.md

@@ -76,6 +76,9 @@ Options:
           Path to directory containing eth2_testnet specs. Defaults to a
           hard-coded Lighthouse testnet. Only effective if there is no existing
           database.
+      --telemetry-collector-url <URL>
+          URL of the OpenTelemetry collector to export tracing spans (e.g.,
+          http://localhost:4317). If not set, tracing export is disabled.
   -V, --version
           Print version
 

book/src/help_vc.md

@@ -134,6 +134,9 @@ Options:
           Path to directory containing eth2_testnet specs. Defaults to a
           hard-coded Lighthouse testnet. Only effective if there is no existing
           database.
+      --telemetry-collector-url <URL>
+          URL of the OpenTelemetry collector to export tracing spans (e.g.,
+          http://localhost:4317). If not set, tracing export is disabled.
       --validator-registration-batch-size <INTEGER>
           Defines the number of validators per validator/register_validator
           request sent to the BN. This value can be reduced to avoid timeouts

book/src/help_vm.md

@@ -77,6 +77,9 @@ Options:
           Path to directory containing eth2_testnet specs. Defaults to a
           hard-coded Lighthouse testnet. Only effective if there is no existing
           database.
+      --telemetry-collector-url <URL>
+          URL of the OpenTelemetry collector to export tracing spans (e.g.,
+          http://localhost:4317). If not set, tracing export is disabled.
 
 Flags:
       --disable-log-timestamp

book/src/help_vm_create.md

@@ -93,6 +93,9 @@ Options:
           Path to directory containing eth2_testnet specs. Defaults to a
           hard-coded Lighthouse testnet. Only effective if there is no existing
           database.
+      --telemetry-collector-url <URL>
+          URL of the OpenTelemetry collector to export tracing spans (e.g.,
+          http://localhost:4317). If not set, tracing export is disabled.
 
 Flags:
       --disable-deposits

book/src/help_vm_import.md

@@ -73,6 +73,9 @@ Options:
           Path to directory containing eth2_testnet specs. Defaults to a
           hard-coded Lighthouse testnet. Only effective if there is no existing
           database.
+      --telemetry-collector-url <URL>
+          URL of the OpenTelemetry collector to export tracing spans (e.g.,
+          http://localhost:4317). If not set, tracing export is disabled.
       --validators-file <PATH_TO_JSON_FILE>
           The path to a JSON file containing a list of validators to be imported
           to the validator client. This file is usually named "validators.json".

book/src/help_vm_move.md

@@ -82,6 +82,9 @@ Options:
           Path to directory containing eth2_testnet specs. Defaults to a
           hard-coded Lighthouse testnet. Only effective if there is no existing
           database.
+      --telemetry-collector-url <URL>
+          URL of the OpenTelemetry collector to export tracing spans (e.g.,
+          http://localhost:4317). If not set, tracing export is disabled.
       --validators <STRING>
           The validators to be moved. Either a list of 0x-prefixed validator
           pubkeys or the keyword "all".