We should target the following specialisation failures:

• has managed dict
• not in dict (how does this even happen??)

With these two we can hit >90% specialisation successes.
If we're feeling really ambitious, we could aim for "not managed dict" failure too. But we don't need that to achieve >90% successes.

I'm doing the first one. Is anyone interested in investigating the second specialisation failure?

Linked PRs

• gh-100288: Specialise LOAD_ATTR_METHOD for managed dictionaries #100289
• Revert "gh-100288: Specialise LOAD_ATTR_METHOD for managed dictionaries (GH-100289)" #100468
• gh-100288: Specialise LOAD_ATTR_METHOD for managed dictionaries #100492
• GH-100288: Remove LOAD_ATTR_METHOD_WITH_DICT instruction. #100753
• GH-100288: Skip extra work when failing to specialize LOAD_ATTR #101354
• GH-100288: Specialize class attribute loads #101379
• GH-100288: Specialize LOAD_ATTR for simple class attributes. #105990
• GH-100288: regen cases after #105990 #106589