Fix concurrency issue in DeadlockThreadRegistry
#### Description

If addDeadlockedThread and getDeadlockedThreadIdSet operation performed concurrently on deadlockedThreadIdSet in DeadlockThreadRegistry class.

Concurrency issue will occur.
```java
public class DeadlockThreadRegistry implements DeadlockThreadLocator {

    private final Set<Long> deadlockedThreadIdSet = new HashSet<Long>();

    boolean addDeadlockedThread(long threadId);

    public Set<Long> getDeadlockedThreadIdSet();
}
```


related issue #2941 

