This PR:

• Counts number of actually tracked objects, instead of trackable objects. This ensures that untracking tuples has the desired effect of reducing GC overhead
• Does not track most untrackable tuples during creation. This prevents large numbers of small tuples causing excessive GCs.

For the example in the original report this makes performance on main a bit better than 3.13.

Benchmarking results show this is about neutral on performance otherwise.

• Issue: Potentially serious regression in garbage collector performance in Python 3.14 #139951