Drop the lint expectations clippy 1.98 no longer fulfils - #8564

• This PR follows our AI policy

Summary

The three clippy jobs and the WASM check fail on current stable for any pull request, whatever it touches:

error: this lint expectation is unfulfilled
   --> crates/host_env/src/fileutils.rs:449:5
    |
449 |     clippy::std_instead_of_core,
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: false positive: core::io::ErrorKind is unstable (core_io)
    = note: `-D unfulfilled-lint-expectations` implied by `-D warnings`

clippy::std_instead_of_core no longer fires at four of the places that carry an #[expect] for it, all four written for the same false positive on items whose core counterpart is still unstable. Once the lint stops firing, unfulfilled_lint_expectations turns each of those attributes into an error under -D warnings, and the crate fails to check.

Removing the four is enough. The other two #[expect(clippy::std_instead_of_core)] in the tree, in crates/host_env/src/posix.rs and crates/vm/src/stdlib/_signal.rs, still fire, so they stay.

Test Plan

rustc 1.98.0 (88d9e12ae 2026-08-18) in a Debian container.

The command CI runs, with the same flags:

cargo clippy --keep-going --no-default-features \
  --features stdlib,importlib,stdio,encodings,sqlite,ssl-rustls-aws-lc,host_env \
  --workspace --all-targets \
  --exclude rustpython_wasm --exclude rustpython-compiler-source --exclude rustpython-venvlauncher \
  -- -Dwarnings

finishes clean here. Without the change it stops at crates/host_env/src/fileutils.rs:449, then at crates/vm/src/stdlib/_io.rs:117, then at crates/stdlib/src/pyexpat.rs:4 and crates/stdlib/src/ssl.rs:17. The same four jobs are red on #8561, #8562 and #8563 for the first of those.

Also run: cargo fmt --check, clean, and cargo test --workspace --exclude rustpython_wasm --exclude rustpython-venvlauncher --exclude rustpython-capi, 41 test binaries and no failures.

Summary by CodeRabbit

• Chores
  • Removed obsolete internal lint configuration.
  • No user-facing behavior, functionality, or public API changes.