Update links at end of Windows installer

[zooba]

The last page of the Windows installer suggests emailing python-list@python.org. This probably still works, but is better replaced with a link to discuss.python.org these days. Specifically, https://discuss.python.org/c/users/7 is the right category to link to.

May as well update the downloads link to point directly to the downloads page.

Linked PRs

• gh-105146: Update links at end of Windows installer #105147
• [3.12] gh-105146: Update links at end of Windows installer (uninstall/repair) (GH-105147) #105167
• [3.11] gh-105146: Update links at end of Windows installer (uninstall/repair) (GH-105147) #105168