#1035: Fix meta-learner random_state handling with check_random_state

[su-jin1425]

Proposed changes

Fixes #1035.

This change normalizes random_state handling in the meta-learner bootstrap paths using scikit-learn's check_random_state.

Specifically:

• Replace direct np.random.RandomState(...) construction with check_random_state(...).
• Allow RandomState instances to be passed without raising a TypeError.
• Update the affected docstrings to reflect the supported random-state types.

The change is limited to the existing random-state handling and does not change the public API behavior for existing integer seeds.

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update (if none of the other choices apply)

Checklist

• I have read the CONTRIBUTING doc
• I have signed the CLA
• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)
• Any dependent changes have been merged and published in downstream modules

Further comments

The reported issue was reproduced on the parent commit: passing a RandomState instance to np.random.RandomState(...) raises a TypeError.

The same input was verified successfully on this commit using check_random_state(...).

The full test suite could not be run locally because the Windows environment blocked a Cython DLL during dependency installation.

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