remove unused reference.confg from DistributedData.LightningDb (#7294)

These configuration values are read from and used by `DistributedData/reference.conf`, so this unused duplicate file is confusing and unnecessary.

src/contrib/cluster/Akka.Cluster.Sharding.Tests/PersistentShardingMigrationSpec.cs

@@ -21,7 +21,7 @@ namespace Akka.Cluster.Sharding.Tests
 {
     /// <summary>
     /// Test migration from old persistent shard coordinator with remembered
-    /// entities to using a ddatabacked shard coordinator with an event sourced
+    /// entities to using a ddata-backed shard coordinator with an event sourced
     /// replicated entity store.
     /// </summary>
     public class PersistentShardingMigrationSpec : AkkaSpec
@@ -171,11 +171,11 @@ class = ""Akka.Cluster.Sharding.Tests.MemorySnapshotStoreShared, Akka.Cluster.Sh
                 }");
 
 
-        private Config configForNewMode;
+        private readonly Config _configForNewMode;
 
         public PersistentShardingMigrationSpec(ITestOutputHelper helper) : base(SpecConfig, helper)
         {
-            configForNewMode = ConfigForNewMode.WithFallback(Sys.Settings.Config);
+            _configForNewMode = ConfigForNewMode.WithFallback(Sys.Settings.Config);
         }
 
         protected override void AtStartup()
@@ -187,7 +187,7 @@ protected override void AtStartup()
         [Fact]
         public void Migration_should_allow_migration_of_remembered_shards_and_not_allow_going_back()
         {
-            var typeName = "Migration";
+            const string typeName = "Migration";
 
             WithSystem(Sys.Settings.Config, typeName, "OldMode", (_, region, _) =>
             {
@@ -200,16 +200,28 @@ public void Migration_should_allow_migration_of_remembered_shards_and_not_allow_
                 ExpectMsg("ack");
             });
 
-            WithSystem(configForNewMode, typeName, "NewMode", (system, region, rememberedEntitiesProbe) =>
+            WithSystem(_configForNewMode, typeName, "NewMode", (system, region, rememberedEntitiesProbe) =>
             {
                 AssertRegionRegistrationComplete(region);
                 var probe = CreateTestProbe(system);
                 region.Tell(new Message(1), probe.Ref);
                 probe.ExpectMsg("ack");
-                ImmutableHashSet.Create(
-                    rememberedEntitiesProbe.ExpectMsg<string>(),
-                    rememberedEntitiesProbe.ExpectMsg<string>(),
-                    rememberedEntitiesProbe.ExpectMsg<string>()).Should().BeEquivalentTo("1", "2", "3"); // 1-2 from the snapshot, 3 from a replayed message
+
+                // due to retries in the remember-entities system, we have to tolerate
+                // potentially receiving a duplicate message for the same entity
+                // therefore, we need to wait for at least 3 distinct messages or until the timeout
+                var maxTimeout = TimeSpan.FromSeconds(5);
+                var found = ImmutableHashSet<string>.Empty;
+                Within(maxTimeout, () =>
+                {
+                    while(found.Count < 3 && RemainingOrDefault > TimeSpan.Zero)
+                    {
+                        var msg = rememberedEntitiesProbe.ExpectMsg<string>();
+                        found = found.Add(msg);
+                    }
+                });
+                
+                found.Should().BeEquivalentTo("1", "2", "3"); // 1-2 from the snapshot, 3 from a replayed message
                 rememberedEntitiesProbe.ExpectNoMsg();
             });
 
@@ -224,11 +236,11 @@ public void Migration_should_allow_migration_of_remembered_shards_and_not_allow_
         [Fact]
         public void Migration_should_not_allow_going_back_to_persistence_mode_based_on_a_snapshot()
         {
-            var typeName = "Snapshots";
-            WithSystem(configForNewMode, typeName, "NewMode", (system, region, _) =>
+            const string typeName = "Snapshots";
+            WithSystem(_configForNewMode, typeName, "NewMode", (system, region, _) =>
             {
                 var probe = CreateTestProbe(system);
-                for (int i = 1; i <= 5; i++)
+                for (var i = 1; i <= 5; i++)
                 {
                     region.Tell(new Message(i), probe.Ref);
                     probe.ExpectMsg("ack");

src/contrib/cluster/Akka.DistributedData.LightningDB/Akka.DistributedData.LightningDB.csproj

@@ -8,7 +8,6 @@
     </PropertyGroup>
 
     <ItemGroup>
-        <EmbeddedResource Include="reference.conf"/>
         <ProjectReference Include="..\Akka.DistributedData\Akka.DistributedData.csproj"/>
     </ItemGroup>