Deprecate x86_64 macOS CLI binaries

[epompeii]

GitHub will soon discontinue providing free macOS x86_64 runners for public repositories. Apple has also announced their plans for discontinuing support for the x86_64 architecture.

In accordance with these changes, the Rust project is in the process of demoting the x86_64-apple-darwin target from Tier 1 with host tools to Tier 2 with host tools. This means that the target, including tools like rustc and cargo, will be guaranteed to build but is not guaranteed to pass our automated test suite.

https://blog.rust-lang.org/2025/08/07/Rust-1.89.0/#demoting-x86-64-apple-darwin-to-tier-2-with-host-tools

https://blog.rust-lang.org/2025/08/19/demoting-x86-64-apple-darwin-to-tier-2-with-host-tools/