Remove any instance quota in tempest_scenario
The next testcase can reach the default limit if lots of computes
available [1].
tempest.scenario.test_server_multinode.TestServerMultinode.test_schedule_to_all_nodes
[1] http://artifacts.opnfv.org/functest/functest-opnfv-functest-smoke-hunter-tempest_scenario-run-325/results/tempest_scenario/test_raw_list.txt
Change-Id: Ibf68e2a367199afee3f6198ebf683be6cd938d94
Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>
(cherry picked from commit
bbe8c3e48543eca31493cf33b02e1d9a48de2280)