This change collapses all metrics aggregations classes into a single package `org.elasticsearch.aggregations.metrics`.
It also restricts the visibility of some classes (aggregators and factories) that should not be used outside of the package.
Relates #22868
This PR removes previously deprecated `isShardsAcked()` method in
favour of `isShardsAcknowledged()` on `CreateIndexResponse`, `CreateIndexClusterStateUpdateResponse` and `RolloverResponse`
Related to #27784
Follow-up of #27819
Lisa Cawley
Nik Everett
Jim Ferenczi
Ryan Ernst
olcbean