Send/Recv Participation one at a time

Sending all, then attempting to receive all in an expected order, wasn't working
even with notable delays between sending messages. This points to the mempool
not working as expected...

tests/coordinator/src/tests/key_gen.rs

@@ -30,7 +30,8 @@ pub async fn key_gen<C: Ciphersuite>(
   // This is distinct from the result of evrf_public_keys for each processor, as there'll have some
   // ordering algorithm on-chain which won't match our ordering
   let mut evrf_public_keys_as_on_chain = None;
-  for (i, processor) in processors.iter_mut().enumerate() {
+  for processor in processors.iter_mut() {
+    // Receive GenerateKey
     let msg = processor.recv_message().await;
     match &msg {
       CoordinatorMessage::KeyGen(messages::key_gen::CoordinatorMessage::GenerateKey {
@@ -59,30 +60,33 @@ pub async fn key_gen<C: Ciphersuite>(
         evrf_public_keys: evrf_public_keys_as_on_chain.clone().unwrap(),
       })
     );
+  }
 
-    processor
+  for i in 0 .. coordinators {
+    // Send Participation
+    processors[i]
       .send_message(messages::key_gen::ProcessorMessage::Participation {
         session,
         participation: vec![u8::try_from(u16::from(participant_is[i])).unwrap()],
       })
       .await;
 
-    // Sleep so this participation gets included, before moving to the next participation
-    wait_for_tributary().await;
-    wait_for_tributary().await;
-  }
+    // Sleep so this participation gets included
+    for _ in 0 .. 2 {
+      wait_for_tributary().await;
+    }
 
-  wait_for_tributary().await;
-  for processor in processors.iter_mut() {
-    #[allow(clippy::needless_range_loop)] // This wouldn't improve readability/clarity
-    for i in 0 .. coordinators {
+    // Have every other processor recv this message too
+    for processor in processors.iter_mut() {
       assert_eq!(
         processor.recv_message().await,
-        CoordinatorMessage::KeyGen(messages::key_gen::CoordinatorMessage::Participation {
-          session,
-          participant: participant_is[i],
-          participation: vec![u8::try_from(u16::from(participant_is[i])).unwrap()],
-        })
+        messages::CoordinatorMessage::KeyGen(
+          messages::key_gen::CoordinatorMessage::Participation {
+            session,
+            participant: participant_is[i],
+            participation: vec![u8::try_from(u16::from(participant_is[i])).unwrap()],
+          }
+        )
       );
     }
   }