Improve feature metrics join
- fix bug in the feature metrics logic that ensures there is a row for each wiki/page/time_bucket, e.g. in case no feature metrics exist for a given month.
- improve the
get_all_timebuckets
logic to only createtime_bucket
entries for buckets after the article creation time_bucket. This had a much larger impact than I thought on file size and runtime. - add test for
get_all_timebuckets