In commit 4c7c66dc (gitlab-ci: Add jobs to make Windows x86_64 and
i386 packages, 2022-05-19, v3.24.0-rc1~112^2) we used a separate Windows
packaging job in nightly packaging pipelines.  It did not run in release
pipelines, where we need to run the final packaging step manually with
signing.  Simplify nightly packaging pipelines by running `cpack` at the
end of the build job as we do for other platforms.

For release packaging pipelines, create an archive of the files needed
to build a package, and present this as the built "package" on Windows.