I see this in logs on server shutdown:

```
2022.01.30 02:51:22.856463 [ 755777 ] {} <Error> void DB::MergeTreeBackgroundExecutor<DB::MergeMutateRuntimeQueue>::routine(DB::TaskRuntimeDataPtr) [Queue = DB::MergeMutateRuntimeQueue]: Code: 236. DB::Exception: Cancelled merging parts.
```

but it's not an error.

Log level should be changed and it should not show stack trace.
#include <Storages/MergeTree/MergeTreeBackgroundExecutor.h>
#include <algorithm>
#include <Common/setThreadName.h>
#include <Storages/MergeTree/BackgroundJobsAssignee.h>
namespace DB
{
template <class Queue>
void MergeTreeBackgroundExecutor<Queue>::wait()