[Vega] Default visualization doesn't work on master branch (v8)

[alexwizp]

Kibana version:
v8 (master branch)

Describe the bug:
[Vega] Default visualization doesn't work on master branch (v8)

Steps to reproduce:

1. Navigate to Visualize Library and create new Vega visualization

Screenshots (if relevant):

Screen.Recording.2021-07-23.at.7.33.34.PM.mov

Any additional context:
This visualization still based on deprecated the interval parameter for date histogram aggregation.
Important: for backward compatibility we want to keep the existing and documented spec value interval: {% autointerval%: true}. The fix should be at the level of spec parsing

For more details see: https://www.elastic.co/guide/en/elasticsearch/reference/current/search-aggregations-bucket-datehistogram-aggregation.html

[elasticmachine]

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

[stratoula]

@alexwizp we already tracking this here #106352

[alexwizp]

Duplicate of #106352