Remove unnecessary RPC boxing (#11434)

substrate/client/beefy/rpc/src/lib.rs

@@ -146,11 +146,9 @@ where
 			if let Some(mut sink) = pending.accept() {
 				sink.pipe_from_stream(stream).await;
 			}
-		}
-		.boxed();
+		};
 
-		self.executor
-			.spawn("substrate-rpc-subscription", Some("rpc"), fut.map(drop).boxed());
+		self.executor.spawn("substrate-rpc-subscription", Some("rpc"), fut.boxed());
 	}
 
 	async fn latest_finalized(&self) -> RpcResult<Block::Hash> {

substrate/client/finality-grandpa/rpc/src/lib.rs

@@ -113,11 +113,9 @@ where
 			if let Some(mut sink) = pending.accept() {
 				sink.pipe_from_stream(stream).await;
 			}
-		}
-		.boxed();
+		};
 
-		self.executor
-			.spawn("substrate-rpc-subscription", Some("rpc"), fut.map(drop).boxed());
+		self.executor.spawn("substrate-rpc-subscription", Some("rpc"), fut.boxed());
 	}
 
 	async fn prove_finality(

substrate/client/rpc/src/author/mod.rs

@@ -210,10 +210,8 @@ where
 			};
 
 			sink.pipe_from_stream(stream).await;
-		}
-		.boxed();
+		};
 
-		self.executor
-			.spawn("substrate-rpc-subscription", Some("rpc"), fut.map(drop).boxed());
+		self.executor.spawn("substrate-rpc-subscription", Some("rpc"), fut.boxed());
 	}
 }

substrate/client/rpc/src/chain/chain_full.rs

@@ -147,8 +147,7 @@ fn subscribe_headers<Block, Client, F, G, S>(
 		if let Some(mut sink) = pending.accept() {
 			sink.pipe_from_stream(stream).await;
 		}
-	}
-	.boxed();
+	};
 
-	executor.spawn("substrate-rpc-subscription", Some("rpc"), fut.map(drop).boxed());
+	executor.spawn("substrate-rpc-subscription", Some("rpc"), fut.boxed());
 }

substrate/client/rpc/src/state/state_full.rs

@@ -404,11 +404,9 @@ where
 			if let Some(mut sink) = pending.accept() {
 				sink.pipe_from_stream(stream).await;
 			}
-		}
-		.boxed();
+		};
 
-		self.executor
-			.spawn("substrate-rpc-subscription", Some("rpc"), fut.map(drop).boxed());
+		self.executor.spawn("substrate-rpc-subscription", Some("rpc"), fut.boxed());
 	}
 
 	fn subscribe_storage(&self, pending: PendingSubscription, keys: Option<Vec<StorageKey>>) {
@@ -451,11 +449,9 @@ where
 			if let Some(mut sink) = pending.accept() {
 				sink.pipe_from_stream(stream).await;
 			}
-		}
-		.boxed();
+		};
 
-		self.executor
-			.spawn("substrate-rpc-subscription", Some("rpc"), fut.map(drop).boxed());
+		self.executor.spawn("substrate-rpc-subscription", Some("rpc"), fut.boxed());
 	}
 
 	async fn trace_block(