Stabilise the venv `no-distutils-patch` preview feature

[edmorley]

In #20222 the venv distutils monkeypatch (_virtualenv.pth) is now skipped if on Python 3.10+, but only when the preview feature no-distutils-patch is enabled.

This preview feature was first released in 0.11.29, though missed being stabilised in 0.12 presumably because it landed 2 days after the provisional stabilisation list was drafted in #20185.

Filing this to track its stabilisation in a future major release :-)

[zanieb]

Yeah I prefer changes go through a longer stabilization period. We can do this in the next breaking release though.

[edmorley]

Yeah makes sense! 0.13 sounds great, thank you 💜

[konstin]

If we can make a case that this patch is some sort of problem, we can stabilize outside of a breaking release, virtualenv also already shipped this successfully.