Replace legacy seeded_test fixture with NumPy Generator in tests

[KillerB-O]

Description

This change removes the legacy seeded_test fixture, which relied onnp.random.seed, and introduces a pytest rng fixture built on np.random.default_rng.

Tests that previously depended on seeded_test were updated to use the fixture-provided generator, avoiding reliance on global NumPy random state. This improves test isolation and aligns the test suite with NumPy’s recommended random number API, while preserving reproducible behavior via a fixed seed.

Summary of changes

• Removed the seeded_test fixture from conftest.py
• Updated tests that depended on it to use the rng fixture
• Replaced legacy np.random.* calls in tests that depended on seeded_test with the corresponding Generator (rng.*) methods where applicable

Rationale

• Avoids global random state in tests
• Improves determinism and isolation
• Aligns with modern NumPy testing practices

Related Issue

• Closes Get rid of seeded_test fixture #8035

Checklist

• Checked that the pre-commit linting/style checks pass
• Included tests that prove the fix is effective or that the new feature works
• Added necessary documentation (not required for this change)

Type of change

• New feature / enhancement
• Bug fix
• Documentation
• Maintenance
• Other (please specify):

[KillerB-O]

/pre-commit.ci autofix