Fix on-different-forks metrics during initialization (#1468)

* fix on-different-forks metrics during initialization

* "initialize" parachain finality pallet in on-demand parachains relay

* decrease converstion rate requests count

* more error logging

* fix compilation

* clippy

bridges/primitives/chain-kusama/src/lib.rs

@@ -117,7 +117,7 @@ sp_api::decl_runtime_apis! {
 	/// Kusama runtime itself.
 	pub trait KusamaFinalityApi {
 		/// Returns number and hash of the best finalized header known to the bridge module.
-		fn best_finalized() -> (BlockNumber, Hash);
+		fn best_finalized() -> Option<(BlockNumber, Hash)>;
 	}
 
 	/// Outbound message lane API for messages that are sent to Kusama chain.

bridges/primitives/chain-millau/src/lib.rs

@@ -314,7 +314,7 @@ sp_api::decl_runtime_apis! {
 	/// Millau runtime itself.
 	pub trait MillauFinalityApi {
 		/// Returns number and hash of the best finalized header known to the bridge module.
-		fn best_finalized() -> (BlockNumber, Hash);
+		fn best_finalized() -> Option<(BlockNumber, Hash)>;
 	}
 
 	/// Outbound message lane API for messages that are sent to Millau chain.

bridges/primitives/chain-polkadot/src/lib.rs

@@ -118,7 +118,7 @@ sp_api::decl_runtime_apis! {
 	/// Polkadot runtime itself.
 	pub trait PolkadotFinalityApi {
 		/// Returns number and hash of the best finalized header known to the bridge module.
-		fn best_finalized() -> (BlockNumber, Hash);
+		fn best_finalized() -> Option<(BlockNumber, Hash)>;
 	}
 
 	/// Outbound message lane API for messages that are sent to Polkadot chain.

bridges/primitives/chain-rialto-parachain/src/lib.rs

@@ -241,7 +241,7 @@ sp_api::decl_runtime_apis! {
 	/// RialtoParachain runtime itself.
 	pub trait RialtoParachainFinalityApi {
 		/// Returns number and hash of the best finalized header known to the bridge module.
-		fn best_finalized() -> (BlockNumber, Hash);
+		fn best_finalized() -> Option<(BlockNumber, Hash)>;
 	}
 
 	/// Outbound message lane API for messages that are sent to RialtoParachain chain.

bridges/primitives/chain-rialto/src/lib.rs

@@ -262,7 +262,7 @@ sp_api::decl_runtime_apis! {
 	/// Rialto runtime itself.
 	pub trait RialtoFinalityApi {
 		/// Returns number and hash of the best finalized header known to the bridge module.
-		fn best_finalized() -> (BlockNumber, Hash);
+		fn best_finalized() -> Option<(BlockNumber, Hash)>;
 	}
 
 	/// Outbound message lane API for messages that are sent to Rialto chain.

bridges/primitives/chain-rococo/src/lib.rs

@@ -113,7 +113,7 @@ sp_api::decl_runtime_apis! {
 	/// Rococo runtime itself.
 	pub trait RococoFinalityApi {
 		/// Returns number and hash of the best finalized header known to the bridge module.
-		fn best_finalized() -> (BlockNumber, Hash);
+		fn best_finalized() -> Option<(BlockNumber, Hash)>;
 	}
 
 	/// Outbound message lane API for messages that are sent to Rococo chain.

bridges/primitives/chain-westend/src/lib.rs

@@ -106,6 +106,6 @@ sp_api::decl_runtime_apis! {
 	/// Westend runtime itself.
 	pub trait WestendFinalityApi {
 		/// Returns number and hash of the best finalized header known to the bridge module.
-		fn best_finalized() -> (BlockNumber, Hash);
+		fn best_finalized() -> Option<(BlockNumber, Hash)>;
 	}
 }

bridges/primitives/chain-wococo/src/lib.rs

@@ -70,7 +70,7 @@ sp_api::decl_runtime_apis! {
 	/// Wococo runtime itself.
 	pub trait WococoFinalityApi {
 		/// Returns number and hash of the best finalized header known to the bridge module.
-		fn best_finalized() -> (BlockNumber, Hash);
+		fn best_finalized() -> Option<(BlockNumber, Hash)>;
 	}
 
 	/// Outbound message lane API for messages that are sent to Wococo chain.

bridges/primitives/header-chain/src/lib.rs

@@ -88,7 +88,7 @@ pub trait InclusionProofVerifier {
 /// A trait for pallets which want to keep track of finalized headers from a bridged chain.
 pub trait HeaderChain<H, E> {
 	/// Get the best finalized header known to the header chain.
-	fn best_finalized() -> H;
+	fn best_finalized() -> Option<H>;
 
 	/// Get the best authority set known to the header chain.
 	fn authority_set() -> AuthoritySet;
@@ -98,8 +98,8 @@ pub trait HeaderChain<H, E> {
 }
 
 impl<H: Default, E> HeaderChain<H, E> for () {
-	fn best_finalized() -> H {
-		H::default()
+	fn best_finalized() -> Option<H> {
+		None
 	}
 
 	fn authority_set() -> AuthoritySet {