ipatests: Test that a user can be issued multiple certificates
    
    Prevent regressions in the LDAP cache layer that caused newly
    issued certificates to overwrite existing ones.
    
    https://pagure.io/freeipa/issue/8986
    
    Signed-off-by: Rob Crittenden <rcritten@redhat.com>
    Reviewed-By: Francois Cami <fcami@redhat.com>
    Reviewed-By: Fraser Tweedale <ftweedal@redhat.com>