Correct keyring provider default

[Darsstar]

Correct the default for --keyring-provider from disabled to auto. See #11939.

[sbidoul]

I understand this needs to go in 23.1, since the incorrect default was not released yet ?

I'm tentatively adding this to 23.1 but I'll let other maintainers review this as I'm not familiar with the keyring aspect of pip.

[sbidoul]

Also is it correct that this does not need a changelog because this was never released?

[pfmoore]

So to be clear, #11698 (merged, and currently going to be released with 23.1) breaks backward compatibility by switching the default to disabled, but wrongly states otherwise in the docs. This PR fixes that to make the compatible behaviour the default, as was the original plan.

I'm good with getting this fixed. The fix looks fine to me, and the tests pass (although I don't fully follow them) so I'm going to hit merge on this. Thanks for sorting out a fix @Darsstar!