network: Rename peerset metric to peerstore metric

[lexnv]

The substrate_sub_libp2p_peerset_num_discovered corresponds to the PeerStoreMetric object and is reported by the peerstore itself, not by the peerset (protocol controller of notifications).

polkadot-sdk/substrate/client/network/src/service/metrics.rs

Lines 220 to 244 in 1a701c9

	pub struct PeerStoreMetrics {
	pub num_banned_peers: Gauge<U64>,
	pub num_discovered: Gauge<U64>,
	}
	impl PeerStoreMetrics {
	pub fn register(registry: &Registry) -> Result<Self, PrometheusError> {
	Ok(Self {
	num_banned_peers: prometheus::register(
	Gauge::new(
	"substrate_sub_libp2p_peerset_num_banned_peers",
	"Number of banned peers stored in the peerset manager",
	)?,
	registry,
	)?,
	num_discovered: prometheus::register(
	Gauge::new(
	"substrate_sub_libp2p_peerset_num_discovered",
	"Number of nodes stored in the peerset manager",
	)?,
	registry,
	)?,
	})
	}
	}

cc @paritytech/networking