Fix monkeypatch.setattr/delattr binding descriptors when raising=False

[IMGillusion]

Fixes #10646.

When monkeypatch.setattr/monkeypatch.delattr are called with raising=False, the attribute existence check currently uses getattr/hasattr, which binds descriptors on the target. This can cause unwanted side effects (e.g. a descriptor __get__ raising, running setup code, or mutating state) even though the caller explicitly disabled the check.

This change makes the raising=False path probe the attribute with inspect.getattr_static, which reads the attribute from the object/class dicts without invoking __get__. The raising=True path is unchanged: it still binds descriptors on purpose, since it needs to detect descriptors that raise AttributeError on access.

Red/green verified: with the new tests (a RaisingDescriptor whose __get__ always fails), raising=True still binds as before while raising=False no longer does, for both setattr and delattr on classes and instances; undo restores the original descriptor. Full test_monkeypatch.py plus test_main/test_collection/test_assertion pass (377 passed), ruff and mypy clean.

AI Disclosure

This PR was developed with the assistance of an AI agent; the account owner verified the root-cause analysis, the red/green test results, and the full test-suite run before submitting.