* [ML] Addressing bug streaming DatafeedConfig aggs from (<= 6.5.4) -> 6.7.0 (#40610)
* Addressing stream failure and adding tests to catch such in the future
* Add aggs to full cluster restart tests
* Test BWC for datafeeds with and without aggs
The wire serialisation is different for null/non-null
aggs, so it's worth testing both cases.
* Fixing bwc test, removing types
* Fixing BWC test for datafeed
* Update 40_ml_datafeed_crud.yml
* Update build.gradle