[v10.0.x] XYChart: Ensure color scale is field-local and synced with data updates

[grafana-delivery-bot]

Backport 3007e3b from #70480

---

Fixes https://github.com/grafana/support-escalations/issues/6404

there were two issues:

1. the color scale was taken from global min/max of all number fields instead of just the color field. this is the result of doStandardCalcs() and/or getDisplayProcessor() at the PanelQueryRunner level which sets a global & shared min/max on each number field.state.range. i had to hack around this by unsetting the global range we get and re-init the displayProcessor to re-calc the field-local range.
2. the field range that was used was always the one which existed during initial chart setup and was not kept in sync with data updates.

the correct behavior:

xy-color-test

{
  "annotations": {
    "list": [
      {
        "builtIn": 1,
        "datasource": {
          "type": "grafana",
          "uid": "-- Grafana --"
        },
        "enable": true,
        "hide": true,
        "iconColor": "rgba(0, 211, 255, 1)",
        "name": "Annotations & Alerts",
        "type": "dashboard"
      }
    ]
  },
  "editable": true,
  "fiscalYearStartMonth": 0,
  "graphTooltip": 0,
  "id": 724,
  "links": [],
  "liveNow": false,
  "panels": [
    {
      "datasource": {
        "type": "testdata",
        "uid": "PD8C576611E62080A"
      },
      "fieldConfig": {
        "defaults": {
          "color": {
            "mode": "continuous-BlYlRd"
          },
          "custom": {
            "axisCenteredZero": false,
            "axisColorMode": "text",
            "axisLabel": "",
            "axisPlacement": "auto",
            "hideFrom": {
              "legend": false,
              "tooltip": false,
              "viz": false
            },
            "pointSize": {
              "fixed": 50
            },
            "scaleDistribution": {
              "type": "linear"
            },
            "show": "points"
          },
          "mappings": [],
          "thresholds": {
            "mode": "absolute",
            "steps": [
              {
                "color": "green",
                "value": null
              },
              {
                "color": "red",
                "value": 80
              }
            ]
          }
        },
        "overrides": []
      },
      "gridPos": {
        "h": 8,
        "w": 12,
        "x": 0,
        "y": 0
      },
      "id": 1,
      "options": {
        "legend": {
          "calcs": [],
          "displayMode": "list",
          "placement": "bottom",
          "showLegend": true
        },
        "series": [
          {
            "pointColor": {
              "field": "c"
            },
            "x": "x",
            "y": "y"
          }
        ],
        "seriesMapping": "manual",
        "tooltip": {
          "mode": "single",
          "sort": "none"
        }
      },
      "targets": [
        {
          "csvContent": "x,y,c\n0,0,0\n50,50,25\n100,100,50",
          "datasource": {
            "type": "testdata",
            "uid": "PD8C576611E62080A"
          },
          "refId": "A",
          "scenarioId": "csv_content"
        }
      ],
      "title": "Panel Title",
      "type": "xychart"
    }
  ],
  "refresh": "",
  "schemaVersion": 38,
  "style": "dark",
  "tags": [],
  "templating": {
    "list": []
  },
  "time": {
    "from": "now-6h",
    "to": "now"
  },
  "timepicker": {},
  "timezone": "",
  "title": "xy-color-test",
  "uid": "aa6ab0e1-be4b-455c-b06d-a45b27ec63d4",
  "version": 2,
  "weekStart": ""
}

xychart-color-by-field.mp4

[nmarrs]

🫡

[nmarrs]

Not sure that we should consider the @grafana-delivery-bot as an external contributor 🤔