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/statement-distribution/src/lib.rs

@@ -1889,11 +1889,12 @@ mod tests {
 					assert_eq!(s, statement);
 				}
 			);
+			handle.send(FromOverseer::Signal(OverseerSignal::Conclude)).await;
 		};
 
 		futures::pin_mut!(test_fut);
 		futures::pin_mut!(bg);
 
-		executor::block_on(future::select(test_fut, bg));
+		executor::block_on(future::join(test_fut, bg));
 	}
 }