Kibana Lens - Drop partial buckets

@wylie, Thank you for creating and following up on the issues! Certainly it would be helpful if there was a way to drop partial buckets in Lens directly, and I think the TimePicker change to allow "less-than" the end date as an option would be even more valuable. I say that because--after thinking about this issue some more--usually we will have more than one Lens visualization (e.g., a pie chart) alongside the Lens date-histogram data table, in which the date range for the pie chart would be controlled by the TimePicker and not the date-histogram.

In other words, even if I was able to create a Lens data table using a date histogram that dropped partial buckets, all of my other Lens visualizations that don't use a date histogram (e.g., pie charts, metrics, etc.), would still be presenting the spill-over data from the very beginning of the End Date value. Consequently, if a user was to click on "2017", the table might say "1,000,000 downloads" for that year, but the pie chart next to the table might say "1,000,005 downloads" due to an extra 5 downloads having occurred at 2018-01-01 00:00:00. Naturally, this could cause some confusion to the viewer.