Avoid actually setting unlimited value in policy

Author: bording

src/NServiceBus.Transport.RabbitMQ/Administration/BrokerVerifier.cs

@@ -171,7 +171,7 @@ bool ShouldOverrideDeliveryLimit(Queue queue)
 
         var limit = queue.GetDeliveryLimit();
 
-        if (limit == -1)
+        if (limit is Queue.UnlimitedDeliveryLimitIndicatorValue or BigValueInsteadOfActuallyUnlimited)
         {
             return false;
         }
@@ -201,7 +201,7 @@ async Task SetDeliveryLimitViaPolicy(Queue queue, CancellationToken cancellation
         var policy = new Policy
         {
             ApplyTo = PolicyTarget.QuorumQueues,
-            Definition = new PolicyDefinition { DeliveryLimit = -1 },
+            Definition = new PolicyDefinition { DeliveryLimit = BigValueInsteadOfActuallyUnlimited },
             Pattern = queue.Name,
             Priority = 0
         };
@@ -242,4 +242,6 @@ public void Dispose()
         Dispose(disposing: true);
         GC.SuppressFinalize(this);
     }
+
+    const int BigValueInsteadOfActuallyUnlimited = 100_000;
 }

src/NServiceBus.Transport.RabbitMQ/Administration/ManagementApi/Converters/DeliveryLimitConverter.cs

@@ -20,7 +20,7 @@ public override int Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSeri
 
             if (string.Equals(value, "unlimited", StringComparison.OrdinalIgnoreCase))
             {
-                return -1;
+                return Queue.UnlimitedDeliveryLimitIndicatorValue;
             }
 
             throw new JsonException($"Unexpected string value for delivery limit: {value}");

src/NServiceBus.Transport.RabbitMQ/Administration/ManagementApi/Models/Queue.cs

@@ -67,6 +67,8 @@ public int GetDeliveryLimit()
             limit = 0;
         }
 
-        return limit ?? -1;
+        return limit ?? UnlimitedDeliveryLimitIndicatorValue;
     }
+
+    public const int UnlimitedDeliveryLimitIndicatorValue = -1000;
 }