[serverctl] rename remove_cube to drop_cube (closes #4545093)
For the sake of consistency, since commands are currently named:
- add_{cube,entity,attribute,relation}
- drop_{entity,attribute,relation}
- remove_cube
change_attribute_type('CWCache', 'timestamp', 'TZDatetime')
change_attribute_type('CWUser', 'last_login_time', 'TZDatetime')
change_attribute_type('CWSource', 'latest_retrieval', 'TZDatetime')
drop_attribute('CWSource', 'synchronizing')
add_attribute('CWSource', 'in_synchronization')