Error when creating a Top Hit aggregation

[lizozom]

Kibana version:
master, doesn't happen in 7.8

Describe the bug:
Trying to create a Top Hit aggregation fails

Steps to reproduce:

1. Load the a data set
2. Create a new table visualization
3. Choose a Top Hit metric aggregation
4. Choose a keyword field

An error is shown:

{
  "statusCode": 400,
  "error": "Bad Request",
  "message": "[illegal_argument_exception] Field [category.keyword] of type [keyword] does not support custom formats",
  "attributes": {
    "error": {
      "root_cause": [
        {
          "type": "illegal_argument_exception",
          "reason": "Field [category.keyword] of type [keyword] does not support custom formats"
        }
      ],
      "type": "search_phase_execution_exception",
      "reason": "all shards failed",
      "phase": "query",
      "grouped": true,
      "failed_shards": [
        {
          "shard": 0,
          "index": "kibana_sample_data_ecommerce",
          "node": "YjD2azE0SrOEA6beW3T-2w",
          "reason": {
            "type": "illegal_argument_exception",
            "reason": "Field [category.keyword] of type [keyword] does not support custom formats"
          }
        }
      ],
      "caused_by": {
        "type": "illegal_argument_exception",
        "reason": "Field [category.keyword] of type [keyword] does not support custom formats",
        "caused_by": {
          "type": "illegal_argument_exception",
          "reason": "Field [category.keyword] of type [keyword] does not support custom formats"
        }
      }
    }
  }
}

Expected behavior:
Either

• Invalid fields shouldn't be available for the user to choose or
• Aggregation should work

Screenshots (if relevant):

Errors in browser console (if relevant):

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

Any additional context:

[elasticmachine]

Pinging @elastic/kibana-app-arch (Team:AppArch)

[lukeelmers]

I think this issue will be resolved by #47727