dsdb: Remove unused local_password module

dsdb: Remove unused local_password module

This was an idea about how Samba might have worked if passwords were
not safe to be stored in a remote DB (get some kind of LDAP backend).

Nothing ever used this, but it was a nice idea.  But git master is not
the place to preserve history, even interesting ideas like splitting
passwords from the non-password data (possible because, in the same way
we are allowed to encrypt them, we do not allow a search on password
values).

Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Garming Sam <garming@catalyst.net.nz>