FIX: Avoid setting 'p' internal metric parameter when sklearn wouldn't set it

[david-cortes-intel]

Description

KNN classes have an internal attribute effective_metric_params_ which uses a 'p' parameter for minkowski, but it looks like sklearnex is setting this parameter for other metrics too, which leads to sklearn throwing a warning about this parameter being unused when falling back to it, plus ending up with different public-facing attributes than sklearn.

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Checklist:

Completeness and readability

• I have commented my code, particularly in hard-to-understand areas.
• Git commit message contains an appropriate signed-off-by string (see CONTRIBUTING.md for details).
• I have resolved any merge conflicts that might occur with the base branch.

Testing

• I have run it locally and tested the changes extensively.
• All CI jobs are green or I have provided justification why they aren't.
• I have extended testing suite if new functionality was introduced in this PR.

[david-cortes-intel]

/intelci: run

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

Flag	Coverage Δ
azure	79.83% <100.00%> (?)
github	81.85% <100.00%> (-0.02%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
sklearnex/neighbors/common.py	92.26% <100.00%> (-0.23%)	⬇️
sklearnex/neighbors/knn_classification.py	98.64% <ø> (ø)
sklearnex/neighbors/knn_regression.py	100.00% <ø> (ø)
sklearnex/neighbors/knn_unsupervised.py	98.24% <ø> (ø)

... and 26 files with indirect coverage changes

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[david-cortes-intel]

CI error is in model builders, doesn't look related to this PR:

tests/test_model_builders.py::test_treelite_unsupported PASSED
OSError: [WinError 6] The handle is invalid

[david-cortes-intel]

/intelci: run