Resolve duplicate index PropertyConfigurations by choosing the last modify one

In current implementation of the index Augmenter, there is no ideal mechanism to merge duplicate Index PropertyConfiguratons for given kind. It can only pick one. And we can't prevent users from creating duplicate Index PropertyConfiguratons (using same code but different record id) using the Storage Service API.

In the latest pre-ship test of index augmenter, a user created duplicate Index PropertyConfiguratons by mistake and forgot that a duplicate Index PropertyConfiguratons record was created. No matter how the user changed the new one, the Index Augmenter did not take effect on the new one. User had no idea what happened as the new configuration is correct.

We found that it could be a common problem, especially for users who are not aware of the limitation - no conflict/merge strategy is applied on duplicate Index PropertyConfiguations.

Before we can come out better strategy to deal with duplicate Index PropertyConfiguratons, we change the augmenter to pick the last modified one if there are more than one Index PropertyConfiguarations for a given kind and log a warning message. The change is simple and should be safe.