Fix a bug where Recycler's capacity can increase beyond its maximum

/cc @ylgrgyq and @belliottsmith

This one is for 4.0.

Related: #3166

Motivation:

When the recyclable object created at one thread is returned at the other thread, it is stored in a WeakOrderedQueue.

The objects stored in the WeakOrderedQueue is added back to the stack by WeakOrderedQueue.transfer() when the owner thread ran out of recyclable objects.

However, WeakOrderedQueue.transfer() does not have any mechanism that prevents the stack from growing beyond its maximum capacity.

Modifications:

- Make WeakOrderedQueue.transfer() increase the capacity of the stack only up to its maximum
- Add tests for the cases where the recyclable object is returned at the non-owner thread
- Fix a bug where Stack.scavengeSome() does not scavenge the objects when it's the first time it ran out of objects and thus its cursor is null.
- Overall clean-up of scavengeSome() and transfer()

Result:

The capacity of Stack never increases beyond its maximum.