[IMP] crm, product, ...: Clean some common test classes

addons/crm/tests/common.py

addons/crm/tests/test_crm_activity.py

addons/crm/tests/test_crm_lead.py

addons/crm/tests/test_lead2opportunity.py

addons/crm/tests/test_new_lead_notification.py

addons/hr_holidays/tests/common.py

addons/hr_holidays/tests/test_access_rights.py

addons/hr_holidays/tests/test_accrual_allocations.py

addons/hr_holidays/tests/test_automatic_leave_dates.py

addons/hr_holidays/tests/test_change_department.py

addons/hr_holidays/tests/test_holidays_flow.py

addons/hr_holidays/tests/test_hr_leave_type.py

addons/hr_holidays/tests/test_leave_requests.py

addons/hr_holidays/tests/test_out_of_office.py

addons/product/tests/test_product_attribute_value_config.py

addons/project/tests/test_access_rights.py

addons/project/tests/test_portal.py

addons/project/tests/test_project_base.py

addons/project/tests/test_project_flow.py

addons/purchase_stock/tests/common.py