linter: Enable test-rules for test build

[MichaReiser]

Summary

ruff_linter__rules__ruff__tests__RUF101_RUF101 started failing because it relies on the test-rules feature to be enabled in ruff_linter.

This PR enables the test-rules when building for tests or when the feature is enabled.

Test Plan

cargo test -p ruff_linter passes

[github-actions[bot]]

ruff-ecosystem results

Linter (stable)

✅ ecosystem check detected no linter changes.

Linter (preview)

✅ ecosystem check detected no linter changes.