Add some metrics improvements (#15922)

* Define TCP and QUIC as `InternetProtocol` (no functional change).

* Group types. (No functional changes)

* Rename variables and use range syntax.

* Add `p2pMaxPeers` and `p2pPeerCountDirectionType` metrics

* `p2p_subscribed_topic_peer_total`: Reset to avoid dangling values.

* `validateConfig`:
- Use `Warning` with fields instead of `Warnf`.
- Avoid to both modify in place the input value and return it.

* Add `p2p_minimum_peers_per_subnet` metric.

* `beaconConfig` => `cfg`.

https://github.com/OffchainLabs/prysm/pull/15880#discussion_r2436826215

* Add changelog

---------

Co-authored-by: james-prysm <90280386+james-prysm@users.noreply.github.com>

beacon-chain/core/peerdas/validator.go

@@ -84,10 +84,10 @@ func ValidatorsCustodyRequirement(state beaconState.ReadOnlyBeaconState, validat
 		totalNodeBalance += validator.EffectiveBalance()
 	}
 
-	beaconConfig := params.BeaconConfig()
-	numberOfCustodyGroups := beaconConfig.NumberOfCustodyGroups
-	validatorCustodyRequirement := beaconConfig.ValidatorCustodyRequirement
-	balancePerAdditionalCustodyGroup := beaconConfig.BalancePerAdditionalCustodyGroup
+	cfg := params.BeaconConfig()
+	numberOfCustodyGroups := cfg.NumberOfCustodyGroups
+	validatorCustodyRequirement := cfg.ValidatorCustodyRequirement
+	balancePerAdditionalCustodyGroup := cfg.BalancePerAdditionalCustodyGroup
 
 	count := totalNodeBalance / balancePerAdditionalCustodyGroup
 	return min(max(count, validatorCustodyRequirement), numberOfCustodyGroups), nil