MPPTask is not move to cancel thread succesfully in MPPTaskManager::cancelMPPQuery

[windtalker]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

In #5361, we try to move current_task to cancel thread in MPPTaskManager::cancelMPPQuery, so MPPTask can be destruct parallelly:

tiflash/dbms/src/Flash/Mpp/MPPTaskManager.cpp

Line 107 in 4ab1564

thread_manager->schedule(false, "CancelMPPTask", [task = std::move(current_task), &reason] { task->cancel(reason); });

However, it is found that due to llvm's SOO, current_task is actually not moved to cancel thread, in some corner cases, current_task will be destructed inside the loop:

tiflash/dbms/src/Flash/Mpp/MPPTaskManager.cpp

Lines 102 to 108 in 4ab1564

	for (auto it = task_set->task_map.begin(); it != task_set->task_map.end();)
	{
	fmt_buf.fmtAppend("{} ", it->first.toString());
	auto current_task = it->second;
	it = task_set->task_map.erase(it);
	thread_manager->schedule(false, "CancelMPPTask", [task = std::move(current_task), &reason] { task->cancel(reason); });
	}

It is very dangerous to deconstruct mpp task inside the loop since destruct a mpp task before all other mpp tasks are cancelled may cause some deadlock issues.

2. What did you expect to see? (Required)

3. What did you see instead (Required)

4. What is your TiFlash version? (Required)

[windtalker]

duplicated with #5638