bootstrap: Update to fedora 41 base image

[brianmcarey]

What this PR does / why we need it:

Fedora 41 has been released[1] - update bootstrap image to use F41 base

This PR also renames the Dockerfiles for the bootstrap images to Containerfiles

As we are using podman to build and publish[2] the bootstrap and golang
image, it makes more sense for these images to use a Containerfile

[1] https://fedoramagazine.org/announcing-fedora-linux-41/
[2] https://github.com/kubevirt/project-infra/blob/e0f89d2a2ae41deed759fef548c8f4e73362103d/images/publish_multiarch_image.sh#L93C1-L101C9

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

Special notes for your reviewer:

/cc @dhiller

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Release note:

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