Remove unnecessary locking in pjsip transaction and add new API to create a group lock with handler in a single atomic instruction

[ming]

When creating a pjsip transaction with new group lock, it is not necessary to acquire the lock. An advantage of doing this is prevent the establishment of lock ordering, which can later be picked up by thread detection analysis tool as violation of lock ordering.

[ming]

In 4992:

Fixed #1821: Remove unnecessary locking in pjsip transaction and add new API to create a group lock with handler in a single atomic instruction