refactor: simplify shutil usage in workstation backend tests

tests/python/test_workstation_backend.py

@@ -6,12 +6,14 @@ NOT ``getGuestIPAddress`` (which would block 30-60s without VMware Tools).
 
 from __future__ import annotations
 
+import shutil
 import subprocess
 from pathlib import Path
 from typing import Any
 
 import pytest
 
+from ci_orchestrator.backends import workstation as ws_mod
 from ci_orchestrator.backends.errors import BackendNotAvailable, BackendOperationFailed
 from ci_orchestrator.backends.protocol import VmHandle
 from ci_orchestrator.backends.workstation import WorkstationVmrunBackend
@@ -165,8 +167,7 @@ def test_is_running_returns_false_when_absent(
 # ── _resolve_vmrun(explicit=None) paths ───────────────────────────────────────
 
 def test_resolve_vmrun_uses_which(monkeypatch: pytest.MonkeyPatch, fake_vmrun: str) -> None:
-    import shutil as _shutil
+    monkeypatch.setattr(shutil, "which", lambda _name: fake_vmrun)
-    monkeypatch.setattr(_shutil, "which", lambda _name: fake_vmrun)
     backend = WorkstationVmrunBackend()  # no explicit path
     assert backend.vmrun_path == fake_vmrun
 
@@ -174,22 +175,16 @@ def test_resolve_vmrun_uses_which(monkeypatch: pytest.MonkeyPatch, fake_vmrun: s
 def test_resolve_vmrun_uses_default_win_path(
     monkeypatch: pytest.MonkeyPatch, tmp_path: Path
 ) -> None:
-    import shutil as _shutil
-    from ci_orchestrator.backends import workstation as ws_mod
-
     fake_default = tmp_path / "vmrun.exe"
     fake_default.write_bytes(b"")
-    monkeypatch.setattr(_shutil, "which", lambda _name: None)
+    monkeypatch.setattr(shutil, "which", lambda _name: None)
     monkeypatch.setattr(ws_mod, "_DEFAULT_WIN_VMRUN", str(fake_default))
     backend = WorkstationVmrunBackend()
     assert backend.vmrun_path == str(fake_default)
 
 
 def test_resolve_vmrun_raises_when_nothing_found(monkeypatch: pytest.MonkeyPatch) -> None:
-    import shutil as _shutil
+    monkeypatch.setattr(shutil, "which", lambda _name: None)
-    from ci_orchestrator.backends import workstation as ws_mod
-
-    monkeypatch.setattr(_shutil, "which", lambda _name: None)
     monkeypatch.setattr(ws_mod, "_DEFAULT_WIN_VMRUN", "/nonexistent/vmrun.exe")
     with pytest.raises(BackendNotAvailable):
         WorkstationVmrunBackend()