Fix broken test_policy_IO_override test
Fix broken test_policy_IO_override test

Since the existing check depends on how quickly the test
passes, it causes to the unpredictable behavior and may break
the test.

This commit removes the unnecessary dependency on the
current time and leaves only the check that timestamp is 
greater than 0.

Change-Id: I3321e9aba0df52cb78523710b26f310f35801674
Closes-Bug: #1441599

thiagodasilva/swift,daasbank/swift,redhat-openstack/swift,prashanthpai/swift,mjzmjz/swift,larsbutler/swift,mjwtom/swift,levythu/swift,wenhuizhang/swift,Akanoa/swift,takeshineshiro/swift,Seagate/swift,swiftstack/swift,AfonsoFGarcia/swift,tipabu/swift,matthewoliver/swift,bouncestorage/swift,matthewoliver/swift,openstack/swift,smerritt/swift,AfonsoFGarcia/swift,maginatics/swift,daasbank/swift,bkolli/swift,IPVL/swift-kilo,wenhuizhang/swift,mjwtom/swift,gold3bear/swift,nadeemsyed/swift,Akanoa/swift,hurricanerix/swift,hurricanerix/swift,psachin/swift,openstack/swift,shibaniahegde/OpenStak_swift,iostackproject/IO-Bandwidth-Differentiation,redhat-openstack/swift,dencaval/swift,smerritt/swift,levythu/swift,rackerlabs/swift,psachin/swift,matthewoliver/swift,revoer/keystone-8.0.0,matthewoliver/swift,hbhdytf/mac2,dencaval/swift,nadeemsyed/swift,hbhdytf/mac2,tipabu/swift,notmyname/swift,zackmdavis/swift,revoer/keystone-8.0.0,notmyname/swift,tipabu/swift,bradleypj823/swift,hbhdytf/mac2,gold3bear/swift,mjzmjz/swift,bradleypj823/swift,notmyname/swift,clayg/swift,iostackproject/IO-Bandwidth-Differentiation,tipabu/swift,bkolli/swift,openstack/swift,shibaniahegde/OpenStak_swift,thiagodasilva/swift,notmyname/swift,Em-Pan/swift,redbo/swift,smerritt/swift,psachin/swift,clayg/swift,aerwin3/swift,swiftstack/swift,maginatics/swift,hurricanerix/swift,IPVL/swift-kilo,hbhdytf/mac,redbo/swift,zackmdavis/swift,clayg/swift,hurricanerix/swift,takeshineshiro/swift,clayg/swift,williamthegrey/swift,larsbutler/swift,prashanthpai/swift,swiftstack/swift,psachin/swift,hbhdytf/mac,smerritt/swift,Em-Pan/swift,bouncestorage/swift,hbhdytf/mac2,nadeemsyed/swift,nadeemsyed/swift,rackerlabs/swift,aerwin3/swift,Seagate/swift,openstack/swift,williamthegrey/swift