Remove sc_network::NetworkService::register_notifications_protocol and partially refactor Grandpa tests (#7646)

* Remove sc_network::NetworkService::register_notifications_protocol

* Missing calls to .into()

* Wrong crate name

* [WIP] Fix Grandpa tests

* One more passing

* One more. Two to go.

* This one was actually already passing 🎉

* Last one compiles

* Progress

* grandpa: fix voter_persists_its_votes test

* Restore other tests

* Try spawn future later

Co-authored-by: André Silva <andrerfosilva@gmail.com>

substrate/client/network-gossip/src/bridge.rs

@@ -72,11 +72,7 @@ impl<B: BlockT> GossipEngine<B> {
 		validator: Arc<dyn Validator<B>>,
 	) -> Self where B: 'static {
 		let protocol = protocol.into();
-
-		// We grab the event stream before registering the notifications protocol, otherwise we
-		// might miss events.
 		let network_event_stream = network.event_stream();
-		network.register_notifications_protocol(protocol.clone());
 
 		GossipEngine {
 			state_machine: ConsensusGossip::new(validator, protocol.clone()),
@@ -335,8 +331,6 @@ mod tests {
 			unimplemented!();
 		}
 
-		fn register_notifications_protocol(&self, _: Cow<'static, str>) {}
-
 		fn announce(&self, _: B::Hash, _: Vec<u8>) {
 			unimplemented!();
 		}