Request validation error on TSVB after upgrading from 6.8.x to 7.x.x

[bhavyarm]

Kibana version: 7.9.0 BC9

Elasticsearch version: 7.9.0 BC9

Server OS version: darwin_x86_64

Browser version: chrome latest

Browser OS version: OS X

Original install method (e.g. download page, yum, from source, etc.): from staging

Describe the bug: After I upgraded from 6.8.12 to 7.9.0 BC9 - with metricbeat dashboards - TSVB started logging this error in kibana logs.

Logs:

 log   [14:13:45.546] [warning][plugins][visTypeTimeseries][visTypeTimeseries] Request validation error: [query]: types that failed validation:
- [query.0.0.query]: expected value of type [string] but got [Object]
- [query.1]: expected value to equal [null] (saved object id: unsaved). This most likely means your TSVB visualization contains outdated configuration. You can report this problem under https://github.com/elastic/kibana/issues/new?template=Bug_report.md
  log   [14:13:58.398] [warning][plugins][visTypeTimeseries][visTypeTimeseries] Request validation error: [query]: types that failed validation:
- [query.0.0.query]: expected value of type [string] but got [Object]
- [query.1]: expected value to equal [null] (saved object id: unsaved). This most likely means your TSVB visualization contains outdated configuration. You can report this problem under https://github.com/elastic/kibana/issues/new?template=Bug_report.md

Here is the saved object:

export.ndjson.txt
export_with_related.ndjson.txt

[elasticmachine]

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

[bhavyarm]

cc @flash1293