test_memory_cache: Test removing mc without invalidation
    
    Long living clients should be able to reinitialize
    memory cache which was removed but it not initialized.
    
    This patch also remove workaround in test_local_domain.py
    
    Test for:
    https://fedorahosted.org/sssd/ticket/2726
    
    Reviewed-by: Michal Židek <mzidek@redhat.com>
    (cherry picked from commit b28f5fb097e06a97a45e0ae348e506d9d1432cc8)