tests: use future::join instead of future::select (#2813)

* tests/av-store: use future::join instead of future::select

* tests/backing: use future::join instead of future::select

* tests/provisioner: use future::join instead of future::select

* tests/av-dist: use future::join instead of future::select

* tests/av-recovery: use future::join instead of future::select

* tests/bridge: use future::join instead of future::select

* tests/collator-protocol: use future::join instead of future::select

* tests/stmt-dist: use future::join instead of future::select

* fix tests

polkadot/node/network/availability-distribution/src/tests/mod.rs

@@ -50,7 +50,7 @@ fn test_harness<T: Future<Output = ()>>(
 		futures::pin_mut!(test_fut);
 		futures::pin_mut!(subsystem);
 
-		executor::block_on(future::select(test_fut, subsystem));
+		executor::block_on(future::join(test_fut, subsystem)).1.unwrap();
 	}
 }