Option to skip time-based index set rotation if latest index is empty

## What?

There should be an option to prevent time-based index set rotation if the latest index is empty (i.e. no messages were stored).

## Why?

#13099 (#13028) introduced support for skipping time-based rotation if the index set is empty. Index set rotation will still occur, however, if any index in the set contains messages.

In our case, we needed to stop ingesting messages from a particular type of source (which was going into a dedicated index set with 1 day rotation) for a while. The index set still contains older indices with messages, but there are now many empty "newer" indices.

## Your Environment

* Graylog Version: 5.1.5