Fix race condition in integration test

[yycptt]

This is just a temp fix for the race condition of persistence config. The race condition for archiver provider happens only in the integration test as in the test all services shares one archiver provider.

The race condition for persistence config happens because all the services are using the same persistence config (the datastore map in particular) and will retry to modify the maxQPS during start up and use the modified maxQPS value to create a persistence factory.

We need to come up with a better way to resolve this race condition. One idea is to remove all the pointers in the config definition, which makes every copy of persistence config a deep copy.

[coveralls]

Coverage decreased (-0.7%) to 67.262% when pulling c464cd8 on yycptt:fix-int-race into 41f1acc on uber:master.