Add one Jaeger span per relay parent (#2196)

* Add one Jaeger span per relay parent

This adds one Jaeger span per relay parent, instead of always creating
new spans per relay parent. This should improve the UI view, because
subsystems are now grouped below one common span.

* Fix doc tests

* Replace `PerLeaveSpan` to `PerLeafSpan`

* More renaming

* Moare

* Update node/subsystem/src/lib.rs

Co-authored-by: Andronik Ordian <write@reusable.software>

* Skip the spans

* Increase `spec_version`

Co-authored-by: Andronik Ordian <write@reusable.software>

polkadot/node/subsystem/src/errors.rs

@@ -59,15 +59,3 @@ impl core::fmt::Display for ChainApiError {
 }
 
 impl std::error::Error for ChainApiError {}
-
-
-/// A description of an error causing the chain API request to be unservable.
-#[derive(Debug, thiserror::Error)]
-#[allow(missing_docs)]
-pub enum JaegerError {
-	#[error("Already launched the collector thread")]
-	AlreadyLaunched,
-
-	#[error("Missing jaeger configuration")]
-	MissingConfiguration,
-}