Do not hardcode "Others" bucket

[dplanella]

We're using Kibiter 6.1.4 from Bitergia and we've found out that when using bar charts there is an "Others" bucket that is automatically added as an existing bucket to the chart.

@alpgarcia tells us:

unfortunately Others feature is hardcoded into Kibiter. Each query with a size limit will show Others entry aggregating the rest of the documents that matches the query but are not within the selected size. In your case you are showing 25 milestones, so Others appears grouping the rest together.

It seems that this is a feature exclusive to Kibiter and not present at Kibana upstream. If it's needed for Kibiter, it would be nice to make it an opt-in feature (e.g. with a checkbox under Buckets options: "[x] Show others")

For more context:

• Discussion on the Elastic forums
• Discussion on the GitLab Bitergia instance