message: fix CSFLE custom endpoint Case 5
diff: @@ -1238,7 +1238,7 @@ TEST_CASE("Custom endpoint", "[client_side_encryption]") {
  // key: "arn:aws:kms:us-east-1:579766882180:key/89fcc2c4-08b0-4bd9-9f25-e30687b580d0",
  // endpoint: "kms.us-east-2.amazonaws.com"
  // }
  - // Expect this to fail with an exception with a message containing the string: "us-east-1"
  + // Expect this to fail with an exception.
  auto endpoint_error_masterkey =
  document{} << "region"
  << "us-east-1"
  @@ -1246,7 +1246,7 @@ TEST_CASE("Custom endpoint", "[client_side_encryption]") {
  << "arn:aws:kms:us-east-1:579766882180:key/89fcc2c4-08b0-4bd9-9f25-e30687b580d0"
  << "endpoint"
  << "kms.us-east-2.amazonaws.com" << finalize;
  - _run_endpoint_test(&setup_client, endpoint_error_masterkey.view(), "aws", {{"us-east-1"}});
  + _run_endpoint_test(&setup_client, endpoint_error_masterkey.view(), "aws", {{""}});
  // Call client_encryption.createDataKey() with "aws" as the provider and the following
  // masterKey:
  