Removing the last filter of a Live Data column fetches the entries twice

When the last filter constraint of a Live Data column is removed, LiveDataLogic.filter calls removeAllFilters, which fetches the entries, and then fetches them again itself. The first request is aborted, but the server still processes it, and the loading indicator can blink.

Steps to reproduce

1. Open the document index.
2. Type a value in the Title filter and wait for the results.
3. Clear the filter.
4. Look at the network requests: two /rest/liveData/sources/.../entries requests are sent, the first one cancelled.

Expected: one request.