chore: migrate conformance test runner to tokio

[rvagg]

Switch from async-std to tokio runtime and maintain rough test execution time while simplifying the async implementation.

This builds on some of the simplifying work that went in to #2173, but aborts on the use of rayon because of the mutex contention issues that involved. It doesn't make all of the async complexity go away, we use tokio::task::spawn_blocking to run the tasks and use buffer_unordered to control our concurrency, but we don't lose as much code as #2173 did (+148 −641 vs +166 −460 and the whole TEST_VECTOR_PARALLELISM thing still exists here).

[Copilot]

Pull Request Overview

This PR migrates the conformance test runner from the async-std runtime to Tokio’s multi-threaded runtime and simplifies the async flow by using tokio::task::spawn_blocking and futures::stream for concurrency control. It also converts the run_vector function to a synchronous API, updates test vector parsing, and adjusts dependencies accordingly.

• Swap out async-std for Tokio and use buffer_unordered for parallel test execution
• Refactor run_vector to return results synchronously and launch it via spawn_blocking
• Update dependency manifests to remove async-std and add Tokio

Reviewed Changes

Copilot reviewed 6 out of 8 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
testing/conformance/tests/runner.rs	Replaced async-std with Tokio, refactored vector runner
testing/conformance/src/vector.rs	Made seed_blockstore synchronous
testing/conformance/src/lib.rs	Extended report! macro to include failure reasons
testing/conformance/src/actors.rs	Simplified load_bundles by removing intermediate buffer
testing/conformance/benches/bench_drivers.rs	Updated bench to call sync seed_blockstore
testing/conformance/Cargo.toml	Removed async-std, moved futures and added tokio

Comments suppressed due to low confidence (2)

testing/conformance/Cargo.toml:24

• The futures crate was removed from [dependencies] but is still used in runner.rs. Please re-add futures = "0.3.31" to [dependencies] so that the production code compiles.

wasmtime = { workspace = true }

testing/conformance/tests/runner.rs:177

• The doc comment still refers to returning a list of VectorResults but the function now returns a (PathBuf, Vec<VariantResult>) tuple. Please update the comment to match the new signature.

/// Runs a single test vector and returns a list of VectorResults,

[rvagg]

Would close #2144 when ported to v4

[LesnyRumcajs]

LGTM