Activity view is fetching cross-dataset places

[goldpbear]

I discovered a bug in onResetActivity() in our ActivityView, related to the multidataset refactor: when building the list of places associated with each action collection, we are unnecessarily looping over all place collections. As a result we end up submitting a GET request to each place collection endpoint, with the list of places from every other place collection appended, which is a meaningless request to the server.

The fix is straightforward: just eliminate the unnecessary looping.