Regression: in table vis, you can only split a table one level deep

[lukeelmers]

Within the buckets for a table visualization, you can split the tables an arbitrary number of times, nesting them multiple levels deep.

Here's an example using sample flight data on demo.elastic.co, which is currently running v6.3.x (we have also verified this is how it looks in v6.4.x:

Here's the exact same editor configuration running master locally. Note how the table only splits once on the carrier:

This is a regression and should be addressed prior to v6.5 release.

Link to demo page example:

https://demo.elastic.co/app/kibana#/visualize/create?type=table&indexPattern=d3d7af60-4c81-11e8-b3d7-01146121b73d&_g=(refreshInterval:(pause:!t,value:0),time:(from:now-1y,mode:quick,to:now))&_a=(filters:!(),linked:!f,query:(language:kuery,query:''),uiState:(vis:(params:(sort:(columnIndex:!n,direction:!n)))),vis:(aggs:!((enabled:!t,id:'1',params:(),schema:metric,type:count),(enabled:!t,id:'2',params:(field:Carrier,missingBucket:!f,missingBucketLabel:Missing,order:asc,orderBy:_key,otherBucket:!f,otherBucketLabel:Other,row:!t,size:5),schema:split,type:terms),(enabled:!t,id:'3',params:(field:DestWeather,missingBucket:!f,missingBucketLabel:Missing,order:desc,orderBy:_key,otherBucket:!f,otherBucketLabel:Other,row:!t,size:5),schema:split,type:terms),(enabled:!t,id:'4',params:(customInterval:'2h',drop_partials:!f,extended_bounds:(),field:timestamp,interval:M,min_doc_count:1,row:!t,time_zone:America%2FDenver),schema:split,type:date_histogram)),params:(perPage:10,showMeticsAtAllLevels:!f,showMetricsAtAllLevels:!f,showPartialRows:!f,showTotal:!f,sort:(columnIndex:!n,direction:!n),totalFunc:sum),title:'New%20Visualization',type:table))

[lukeelmers]

cc @elastic/kibana-app

[lukeelmers]

The regression seems to have been introduced in #19061

I'm looking into this.