Skip CloseAsync tests due to false positive leak

cpp/src/arrow/filesystem/azurefs_test.cc

@@ -1569,6 +1569,31 @@ class TestAzureFileSystem : public ::testing::Test {
   }
 
   void TestOpenOutputStreamCloseAsync() {
+#if defined(ADDRESS_SANITIZER) || defined(ARROW_VALGRIND)
+    // This false positive leak is similar to the one pinpointed in the
+    // have_false_positive_memory_leak_with_generator() comments above,
+    // though the stack trace is different. It happens when a block list
+    // is committed from a background thread.
+    //
+    // clang-format off
+    // Direct leak of 968 byte(s) in 1 object(s) allocated from:
+    //   #0 calloc
+    //   #1 (/lib/x86_64-linux-gnu/libxml2.so.2+0xe25a4)
+    //   #2 __xmlDefaultBufferSize
+    //   #3 xmlBufferCreate
+    //   #4 Azure::Storage::_internal::XmlWriter::XmlWriter()
+    //   #5 Azure::Storage::Blobs::_detail::BlockBlobClient::CommitBlockList
+    //   #6 Azure::Storage::Blobs::BlockBlobClient::CommitBlockList
+    //   #7 arrow::fs::(anonymous namespace)::CommitBlockList
+    //   #8 arrow::fs::(anonymous namespace)::ObjectAppendStream::FlushAsync()::'lambda'
+    // clang-format on
+    //
+    // TODO perhaps remove this skip once we can rely on
+    // https://github.com/Azure/azure-sdk-for-cpp/pull/5767
+    if (options_.background_writes) {
+      GTEST_SKIP() << "False positive memory leak in libxml2 with CloseAsync";
+    }
+#endif
     ASSERT_OK_AND_ASSIGN(auto fs, AzureFileSystem::Make(options_));
     auto data = SetUpPreexistingData();
     const std::string path = data.ContainerPath("test-write-object");
@@ -1584,6 +1609,12 @@ class TestAzureFileSystem : public ::testing::Test {
   }
 
   void TestOpenOutputStreamCloseAsyncDestructor() {
+#if defined(ADDRESS_SANITIZER) || defined(ARROW_VALGRIND)
+    // See above.
+    if (options_.background_writes) {
+      GTEST_SKIP() << "False positive memory leak in libxml2 with CloseAsync";
+    }
+#endif
     ASSERT_OK_AND_ASSIGN(auto fs, AzureFileSystem::Make(options_));
     auto data = SetUpPreexistingData();
     const std::string path = data.ContainerPath("test-write-object");