[Internal] HttpTimeoutPolicy: Removes Data Plane Writes from being able to be retried (#3607)

* data plane writes no longer failover on timeout

* removed duplication of test\

Author: NaluTripician

Microsoft.Azure.Cosmos/src/HttpClient/HttpTimeoutPolicy.cs

@@ -36,8 +36,8 @@ public static HttpTimeoutPolicy GetTimeoutPolicy(
                 return HttpTimeoutPolicyControlPlaneRetriableHotPath.Instance;
             }
 
-            //Data Plane Read & Write
-            if (!HttpTimeoutPolicy.IsMetaData(documentServiceRequest))
+            //Data Plane Read
+            if (!HttpTimeoutPolicy.IsMetaData(documentServiceRequest) && documentServiceRequest.IsReadOnlyRequest)
             {
                 return HttpTimeoutPolicyDefault.InstanceShouldThrow503OnTimeout;
             }

Microsoft.Azure.Cosmos/tests/Microsoft.Azure.Cosmos.Tests/CosmosHttpClientCoreTests.cs

@@ -258,7 +258,7 @@ async Task<HttpResponseMessage> sendFunc(HttpRequestMessage request, Cancellatio
 
             Assert.AreEqual(3, count, "Should retry 3 times");
         }
-
+ 
         [TestMethod]
         public async Task HttpTimeoutThrow503TestAsync()
         {
@@ -307,8 +307,8 @@ async Task<HttpResponseMessage> sendFunc(HttpRequestMessage request, Cancellatio
             //Data plane read
             await TestScenarioAsync(HttpMethod.Get, ResourceType.Document, HttpTimeoutPolicyDefault.InstanceShouldThrow503OnTimeout, typeof(CosmosException), 3);
 
-            //Data plane write
-            await TestScenarioAsync(HttpMethod.Post, ResourceType.Document, HttpTimeoutPolicyDefault.InstanceShouldThrow503OnTimeout, typeof(CosmosException), 1);
+            //Data plane write (Should throw a 408 OperationCanceledException rather than a 503)
+            await TestScenarioAsync(HttpMethod.Post, ResourceType.Document, HttpTimeoutPolicyDefault.Instance, typeof(TaskCanceledException), 1);
 
             //Meta data read
             await TestScenarioAsync(HttpMethod.Get, ResourceType.Database, HttpTimeoutPolicyDefault.InstanceShouldThrow503OnTimeout, typeof(CosmosException), 3);