[CI][Python] Update builds to use official Python 3.15 Release #52522

Describe the enhancement requested

Python 3.15 final build / release is today: 2026-10-09.

The Python builds should switch from using release candidate builds to the latest build.

This will need to wait for a few upstream places to add the final build... once the official Python build is out, also need astral, manylinux, etc to update.
* See the progress notes in #48191 for where the various builds come from.

Component(s)

Continuous Integration, Python