[CI] Add more extensive pre-release testing CI matrix

See comment: https://github.com/NVIDIA/cccl/issues/653#issuecomment-3761623825

Just running the weekly workflow before tagging release candidates would probably be enough.

It issue can be closed by adding a "Run CI" option to the RC-tagging workflow that will:

1. Run the weekly workflow on a release branch
2. Notify the release slack channel on failure
3. Gate tagging on the CI workflow
4. Enable by default, but allow opt-out for easily manually overriding (infra issues, etc)