TSVB table with Filter Ratio doesn't work with aggregation other than count

[markov00]

Kibana version:
at least since 7.1

Describe the bug:

If you try to create a Table visualization in TSVB, when using a Filter Ratio you can also change the associated aggregation used. If you use something different from Count the request fails with the following message from ES:

parsing exception: Unknown key for a START_OBJECT in [[object Object]].

Steps to reproduce:

1. create a new TSVB table visualization
2. select a field to group by the rows
3. Select Filter Ratio as aggregation and keep the Denominator/Numerator as *
4. Change the Metric aggregation to anything else except Count
5. See the error on the Network tab for the last data request

Expected behavior:
It should use the specific Metric aggregation used. If instead this is expected and only count should work, then removing completely the Metric Aggregation select menu is required.

Screenshots (if relevant):

Errors in browser console (if relevant):
no error in console

Provide logs and/or server output (if relevant):

{"type":"table","61ca57f0-469d-11e7-af02-69e470af7417":{"id":"61ca57f0-469d-11e7-af02-69e470af7417","statusCode":400,"error":{"error":{"root_cause":[{"type":"parsing_exception","reason":"Unknown key for a START_OBJECT in [[object Object]].","line":1,"col":1308}],"type":"parsing_exception","reason":"Unknown key for a START_OBJECT in [[object Object]].","line":1,"col":1308},"status":400},"series":[]}}

[elasticmachine]

Pinging @elastic/kibana-app (Team:KibanaApp)