Switch to cargo sparse registry

[reaperhulk]

rust-lang/cargo#11224 will be in rust 1.68.0 (releasing on March 9). This is a tracking issue for adopting it fully.

• Rebuild container images from infra with latest rustup stable.
• use cargo sparse registry in distro CI #8480
• Upgrade tart base image with latest rustc for arm64 macOS runners.
• Wait for GH to ship 1.68.0 in base images
  • Ubuntu 22.04 (20230313) Image Update actions/runner-images#7279
  • macOS 12 (20230318) Image Update actions/runner-images#7309
  • Windows Server 2022 (20230314) Image Update actions/runner-images#7286
• Add the same key everywhere else 😄
• Delete ~/.cargo/registry/index/ from .github/actions/cache/action.yml since it is no longer needed.