CSHARP-5449: Retry does not work with BulkWrite operations within the session (#1598)

Author: sanych-sun

src/MongoDB.Driver/ClientBulkWriteException.cs

@@ -45,6 +45,25 @@ public ClientBulkWriteException(
             WriteErrors = writeErrors;
             PartialResult = partialResult;
             WriteConcernErrors = writeConcernErrors;
+
+            if (innerException is MongoException innerMongoException)
+            {
+                foreach (var errorLabel in innerMongoException.ErrorLabels)
+                {
+                    AddErrorLabel(errorLabel);
+                }
+            }
+
+            if (writeConcernErrors != null)
+            {
+                foreach (var writeConcernError in writeConcernErrors)
+                {
+                    foreach (var errorLabel in writeConcernError.ErrorLabels)
+                    {
+                        AddErrorLabel(errorLabel);
+                    }
+                }
+            }
         }
 
         /// <summary>

tests/MongoDB.Driver.Tests/UnifiedTestOperations/Matchers/UnifiedErrorMatcher.cs

@@ -114,11 +114,6 @@ private void AssertErrorContains(Exception actualException, string expectedSubst
 
         private void AssertErrorLabelsContain(Exception actualException, IEnumerable<string> expectedErrorLabels)
         {
-            if (actualException is ClientBulkWriteException bulkWriteException)
-            {
-                actualException = bulkWriteException.InnerException;
-            }
-
             var mongoException = actualException.Should().BeAssignableTo<MongoException>().Subject;
             mongoException.ErrorLabels.Should().Contain(expectedErrorLabels);
         }