* Remove DataCounts and ModelSizeStats from Job
* Delete unused ElasticsearchJobDetailsMapper
Conflicts:
elasticsearch/src/main/java/org/elasticsearch/xpack/prelert/job/persistence/ElasticsearchJobDetailsMapper.java
elasticsearch/src/test/java/org/elasticsearch/xpack/prelert/job/persistence/ElasticsearchJobDetailsMapperTests.java
* Add missing mappings for DataCounts
Fixes yaml test failures
* Add test to assert revert a model snapshot sets DataCounts.latest_record_timestamp
* Resolve merge errors
* Add NORELEASE for persisting dataCounts in cluster update
Original commit: elastic/x-pack-elasticsearch@46099d4db6
This change moves the Java code from `/java/apps/engine-node` to `/elasticsearch` so it matches the structure required by X-Pack. This will make it easier to get the gradle build working correct and building the full Pack zip.
Original commit: elastic/x-pack-elasticsearch@2fd6539e85