* Retrofit the Bulk Uploader types combiner [ch2198]
fix usage collector, add comments to formatForBulk
remove unnecessary customizations
* override default format for bulk upload for usage type collectors
* rename to ignoreForInternalUploader
* collectors -> collectorSet
* use constant for kibana_stats type
* example of data formatting for bulk in function comment
* [Stats API] Set API field names per spec
* fix jest tests
* fix api integration test
* trash the original metrics collector
- constantly accumulating stats over time does not align with the existing behavior, which is to reset the stats to 0 whenever they are pulled
* move some logic out of the collector types combiner into inline
- change the signature of sourceKibana
* Make a new stats collector for the API
- to not clear the data when pulling via the api
- fetching is a read-only thing
* isolate data transforms for api data and upload data
* no static methods
* remove external in bytes
* remove the _stats prefix for kibana and reporting
* update jest test snapshot
* fix collector_types_combiner test
* fix usage api
* add test suite todo comment
* reduce some loc change
* roll back mysterious change
* reduce some more loc change
* comment correction
* reduce more loc change
* whitespace
* comment question
* fix cluster_uuid
* fix stats integration test
* fix bulk uploader test, combineTypes is no longer external
* very important comments about the current nature of stats represented and long-term goals
* add stats api tests with/without authentication
* fix more fields to match data model
* fix more tests
* fix jest test
* remove TODO
* remove sockets
* use snake_case for api field names
* restore accidental removal + copy/paste error
* sourceKibana -> getKibanaInfoForStats
* skip usage test on legacy endpoint
* fix api tests
* more comment
* stop putting a field in that used to be omitted
* fix the internal type to ID the usage data for bulk uploader
* correct the kibana usage type value, which is shown as-is in the API
* more fixes for the constants identifying collector types + test against duplicates
* add a comment on a hack, and a whitespace fix
