remove connected disconnected state only (#3868)

* remove connected disconnected state from overseer

* foo

* split new partial

* fix

* refactor init code to not require a `OverseerHandle` when we don't have an overseer

* intermediate

* fixins

* X

* fixup

* foo

* fixup

* docs

* conditional

* Update node/service/src/lib.rs

* review by ladi

polkadot/node/overseer/examples/minimal-example.rs

@@ -29,7 +29,8 @@ use polkadot_node_subsystem_types::messages::{
 use polkadot_overseer::{
 	self as overseer,
 	gen::{FromOverseer, SpawnedSubsystem},
-	AllMessages, AllSubsystems, HeadSupportsParachains, Overseer, OverseerSignal, SubsystemError,
+	AllMessages, AllSubsystems, HeadSupportsParachains, Overseer, OverseerConnector,
+	OverseerSignal, SubsystemError,
 };
 use polkadot_primitives::v1::Hash;
 
@@ -173,8 +174,15 @@ fn main() {
 			.replace_candidate_validation(|_| Subsystem2)
 			.replace_candidate_backing(|orig| orig);
 
-		let (overseer, _handle) =
-			Overseer::new(vec![], all_subsystems, None, AlwaysSupportsParachains, spawner).unwrap();
+		let (overseer, _handle) = Overseer::new(
+			vec![],
+			all_subsystems,
+			None,
+			AlwaysSupportsParachains,
+			spawner,
+			OverseerConnector::default(),
+		)
+		.unwrap();
 		let overseer_fut = overseer.run().fuse();
 		let timer_stream = timer_stream;