Score explanation could provide notice of function score rounding

[LucasBrandt]

Description

As documented by #49402, _score is stored as a float and has a maximum precision. When the total score is large enough, smaller score factor seemingly disappear. This is expected, but _explanation does not explain why the final score value does not reflect the scoring factors it lists.

Here's an example explanation where it would be helpful to be made aware of the rounding:

{
  "value": 300000000.0,
  "description": "min of:",
  "details": [
    {
      "value": 300000000.0,
      "description": "function score, score mode [sum]",
      "details": [
        {
          "value": 300000000.0,
          "description": "field value function: none(doc['plan.directory_ranking_level'].value * factor=1.0E8)",
          "details": []
        },
        {
          "value": 0.3040064,
          "description": "random score function (seed: -1217277296, field: _id)",
          "details": []
        }
      ]
    },
    {
      "value": 3.4028235e+38,
      "description": "maxBoost",
      "details": []
    }
  ]
}

I believe this is related to #11872 and #53158

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