Remove real-overseer 🎉 (#2834)

* remove real-overseer

* overseer: only activate leaves which support parachains

* integrate HeadSupportsParachains into service

* remove unneeded line

polkadot/parachain/test-parachains/adder/collator/Cargo.toml

@@ -37,6 +37,3 @@ sc-service = { git = "https://github.com/paritytech/substrate", branch = "master
 sp-keyring = { git = "https://github.com/paritytech/substrate", branch = "master" }
 
 tokio = { version = "0.2", features = ["macros"] }
-
-[features]
-real-overseer = [ "polkadot-service/real-overseer" ]

polkadot/parachain/test-parachains/adder/collator/README.md

@@ -2,13 +2,13 @@
 
 First start two validators that will run for the relay chain:
 ```sh
-cargo run --features=real-overseer --release -- -d alice --chain rococo-local --validator --alice --port 50551
-cargo run --features=real-overseer --release -- -d bob --chain rococo-local --validator --bob --port 50552
+cargo run --release -- -d alice --chain rococo-local --validator --alice --port 50551
+cargo run --release -- -d bob --chain rococo-local --validator --bob --port 50552
 ```
 
 Next start the collator that will collate for the adder parachain:
 ```sh
-cargo run --features=real-overseer --release -p test-parachain-adder-collator -- --tmp --chain rococo-local --port 50553
+cargo run --release -p test-parachain-adder-collator -- --tmp --chain rococo-local --port 50553
 ```
 
 The last step is to register the parachain using polkadot-js. The parachain id is

polkadot/parachain/test-parachains/adder/collator/tests/integration.rs

@@ -17,9 +17,7 @@
 //! Integration test that ensures that we can build and include parachain
 //! blocks of the adder parachain.
 
-// If this test is failing, make sure to run all tests with the `real-overseer` feature being enabled.
 #[substrate_test_utils::test]
-#[cfg(feature = "real-overseer")]
 async fn collating_using_adder_collator(task_executor: sc_service::TaskExecutor) {
 	use sp_keyring::AccountKeyring::*;
 	use futures::join;