ci: refine race detection workflows

[hayabusa-cloud]

Summary

This PR restores blocking race detector coverage for the required uring CI surfaces. The root package and examples race checks now run against the same skip-defined surfaces as their corresponding required non-race lanes, while hosted-runner-unstable runtime probes remain outside the required lane.

Changes

• Remove the narrow URING_REQUIRED_RACE_TESTS and URING_REQUIRED_RACE_EXAMPLES regex subsets.
• Run the root package race check with the existing required root skip expression.
• Run the examples race check with the existing required examples skip expression.
• Keep the broader newer-kernel and zero-copy runtime probes in the existing non-blocking or dedicated-validation paths.

[Copilot]

Pull request overview

Expands required race-detector coverage in CI to run the same skip-defined test surfaces as the non-race lanes, replacing the previously narrow allow-list subsets.

Changes:

• Drop the URING_REQUIRED_RACE_TESTS and URING_REQUIRED_RACE_EXAMPLES regex env vars.
• Run the root package race step with the required root skip expression (and raise memlock).
• Run the examples race step with the required examples skip expression.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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