[TSVB] Average metric works incorrectly with histogram data type when index pattern contains wildcard

[kertal]

Kibana version:
master, 7.9

Describe the bug:
TSVB support was introduced in #68837. When an index pattern contains a wildcard, average metric time series chart with fields of type histogram are not displayed correctly.

Steps to reproduce:
Add the following data:

PUT histogram-test1
{
  "mappings": {
    "properties": {
      "date": {
        "type": "date" 
      },
      "histogram-title": {
        "type": "text",
        "fields": {
          "keyword": {
            "type": "keyword"
          }
        }
      },
      "histogram-content": {
        "type": "histogram"
      }
    }
  }
}

POST histogram-test1/_doc
{
  "date": "2020-06-24T21:12:13.000Z",
  "histogram-title": "enim veniam et",
  "histogram-content": {
    "values": [
      3.7,
      4.2
    ],
    "counts": [
      227,
      141
    ]
  }
}

POST histogram-test/_doc
{
  "date": "2020-06-23T21:12:13.000Z",
  "histogram-title": "est incididunt sunt",
  "histogram-content": {
    "values": [
      1.8,
      2.4,
      2.6,
      4.9
    ],
    "counts": [
      92,
      101,
      122,
      244
    ]
  }
}

POST histogram-test1/_doc
{
  "date": "2020-06-22T21:12:13.000Z",
  "histogram-title": "qui qui tempor",
  "histogram-content": {
    "values": [
      0.5,
      2.1,
      2.7,
      3,
      3.2,
      3.5,
      4.2,
      5
    ],
    "counts": [
      210,
      168,
      182,
      181,
      97,
      164,
      77,
      2
    ]
  }
}


POST histogram-test1/_doc
{
  "date": "2020-06-21T21:12:13.000Z",
  "histogram-title": "ullamco nisi sunt",
  "histogram-content": {
    "values": [
      1.7,
      4.5,
      4.8
    ],
    "counts": [
      74,
      146,
      141
    ]
  }
}

POST histogram-test1/_doc
{
  "date": "2020-06-20T21:12:13.000Z",
  "histogram-title": "magna eu incididunt",
  "histogram-content": {
    "values": [
      1,
      3.4,
      4.8
    ],
    "counts": [
      103,
      205,
      11
    ]
  }
}

Configure TSVB the following way:



then change the index pattern to contain a wildcard:

And you can no longer the whole histogram field, chart no longer works

[elasticmachine]

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

[stratoula]

@kertal in your data is missing the mapping for histogram-test. So it doesn't take the histogram type. If it is mapped correctly works as expected.

[kertal]

@stratoula thx, that's good news! closing this