MAINT: Reset sys.path if docstrings import fails (pandas-dev#22456)

Follow-up to pandas-devgh-22413.

Author: gfyoung

pandas/tests/scripts/test_validate_docstrings.py

@@ -471,6 +471,9 @@ def import_scripts(self):
             from validate_docstrings import validate_one
             globals()[global_validate_one] = validate_one
         except ImportError:
+            # Remove addition to `sys.path`
+            sys.path.pop()
+
             # Import will fail if the pandas installation is not inplace.
             raise pytest.skip("pandas/scripts directory does not exist")