tempest: ignore 2 unstable tests for Gnocchi
tempest: ignore 2 unstable tests for Gnocchi

2 tests are timeouting too often and it makes our CI unstable.
Let's ignore the tests now.

Change-Id: I0140e774c0ee27926f03c01a972fb76721e71528

openstack/puppet-openstack-integration,openstack/puppet-openstack-integration,openstack/puppet-openstack-integration