Removing a search widget row pivot does not reset the sort select.

[linuspahl]

As you can see in the screenshot, I removed the source row pivot, but the previous configured sorting still persists. This is only a visual bug, the actual sorting is not affected.

Expected Behavior

Removing a search widget row pivot should reset the related sort settings.

Steps to Reproduce

1. Open the search page
2. Create an aggregation, e.g. a data table.
3. Select a row pivot
4. Use the row pivot field for sorting
5. Remove the row pivot

Your Environment

• Graylog Version: 3.2.0-beta.4-SNAPSHOT