Remove jaeger from approval-voting and approval-distribution (#5830)

Jaeger spans were not usable for debugging, see
#4995, but we pay a
price in CPU cost, subsystem-benchmarks show this brings a reduction of
about 10-15% in CPU usage per subsystem, so remove it.

---------

Signed-off-by: Alexandru Gheorghe <alexandru.gheorghe@parity.io>

polkadot/node/core/approval-voting/Cargo.toml

@@ -29,7 +29,6 @@ polkadot-node-subsystem-util = { workspace = true, default-features = true }
 polkadot-overseer = { workspace = true, default-features = true }
 polkadot-primitives = { workspace = true, default-features = true }
 polkadot-node-primitives = { workspace = true, default-features = true }
-polkadot-node-jaeger = { workspace = true, default-features = true }
 
 sc-keystore = { workspace = true }
 sp-consensus = { workspace = true }

polkadot/node/core/approval-voting/benches/approval-voting-regression-bench.rs

@@ -83,8 +83,9 @@ fn main() -> Result<(), String> {
 		("Sent to peers", 63995.2200, 0.01),
 	]));
 	messages.extend(average_usage.check_cpu_usage(&[
-		("approval-distribution", 12.2736, 0.1),
-		("approval-voting", 2.7174, 0.1),
+		("approval-distribution", 0.1, 0.1),
+		("approval-voting", 0.1, 0.1),
+		("approval-voting-parallel", 18.0758, 0.1),
 	]));
 
 	if messages.is_empty() {

polkadot/node/core/approval-voting/src/import.rs

@@ -28,7 +28,6 @@
 //!
 //! We maintain a rolling window of session indices. This starts as empty
 
-use polkadot_node_jaeger as jaeger;
 use polkadot_node_primitives::{
 	approval::{
 		self as approval_types,
@@ -348,13 +347,6 @@ pub(crate) async fn handle_new_head<
 	finalized_number: &Option<BlockNumber>,
 ) -> SubsystemResult<Vec<BlockImportedCandidates>> {
 	const MAX_HEADS_LOOK_BACK: BlockNumber = MAX_FINALITY_LAG;
-	let _handle_new_head_span = state
-		.spans
-		.get(&head)
-		.map(|span| span.child("handle-new-head"))
-		.unwrap_or_else(|| jaeger::Span::new(head, "handle-new-head"))
-		.with_string_tag("head", format!("{:?}", head))
-		.with_stage(jaeger::Stage::ApprovalChecking);
 
 	let header = {
 		let (h_tx, h_rx) = oneshot::channel();
@@ -666,7 +658,6 @@ pub(crate) mod tests {
 			slot_duration_millis: 6_000,
 			clock: Arc::new(MockClock::default()),
 			assignment_criteria: Box::new(MockAssignmentCriteria::default()),
-			spans: HashMap::new(),
 			per_block_assignments_gathering_times: LruMap::new(ByLength::new(
 				MAX_BLOCKS_WITH_ASSIGNMENT_TIMESTAMPS,
 			)),