Slow AutoScalingGroupTest unit tests

[Steve Baker]

2 tests are taking 128 seconds each

tox -epy27 test_parse_with_bad
Ran 4 tests in 128.446s (+0.123s)
PASSED (id=327)
Slowest Tests
Test id Runtime (s)
------------------------------------------------------------------------------------------------------------- -----------
heat.tests.test_autoscaling_update_policy.AutoScalingGroupTest.test_parse_with_bad_update_policy 128.330
heat.tests.test_autoscaling_update_policy.AutoScalingGroupTest.test_parse_with_bad_pausetime_in_update_policy 128.281
heat.tests.test_instance_group_update_policy.InstanceGroupTest.test_parse_with_bad_pausetime_in_update_policy 1.816
heat.tests.test_instance_group_update_policy.InstanceGroupTest.test_parse_with_bad_update_policy 0.902
______________________________________________________ summary _______________________________________________________

[Thomas Herve (therve)]

Handled in https://review.openstack.org/#/c/115129/