Add 'auth_password' in _SANITIZE_KEYS for strutils

Cinder volume drivers may return connection_info with'auth_password',
This is an example[1], to avoid auth_password to be logged in disk,
we should mask its value with "***".

[1] https://github.com/openstack/cinder/blob/master/cinder/volume/drivers/ibm/storwize_svc/__init__.py#L432

Change-Id: Id8b67615efab1171e66b46550d5b01e1964f85a3
Merge "Add 'auth_password' in _SANITIZE_KEYS for strutils"