* [Metrics UI] Change dropLastBucket to dropPartialBuckets
- Change offset calculation to millisecond percission
- Change dropLastBucket to dropPartialBuckets
- Impliment partial bucket filter
- Adding partial bucket filter to metric threshold alerts
* Cleaning up getElasticsearchMetricQuery
* Change timestamp to from_as_string to align to how date_histgram works
* Fixing tests to be more realistic
* fixing types; removing extra imports
* Fixing new mock data to work with previews
* Removing value checks since they don't really provide much value
* Removing test for refactored functinality
* Change value to match millisecond resolution
* Fixing values for new partial bucket scheme
* removing unused var
* Fixing lookback since drops more than last buckets
* Changing results count
* fixing more tests
* Removing empty describe
Co-authored-by: Kibana Machine <42973632+kibanamachine@users.noreply.github.com>