Fixed an issue that produced State timeline panel tooltip error when data was not in sync.

[zoltanbedi]

What this PR does / why we need it:

This PR resolves the issue around state timeline panel's tooltip when data is out of sync.

statetimeline-bug.mp4

statetimeline-fix.mp4

Which issue(s) this PR fixes:

Fixes https://github.com/grafana/support-escalations/issues/932

Special notes for your reviewer:

Repro step:
I've used the tns-demo to generate data.

1. Add a state timeline panel with 2 queries from Loki
2. Set auto refresh to 10s
3. Hover over panel data

Panel json

{
  "id": 23763571993,
  "gridPos": {
    "h": 8,
    "w": 12,
    "x": 0,
    "y": 0
  },
  "type": "state-timeline",
  "title": "Panel Title",
  "datasource": "tns-loki",
  "fieldConfig": {
    "defaults": {
      "custom": {
        "lineWidth": 5,
        "fillOpacity": 76
      },
      "color": {
        "mode": "thresholds"
      },
      "thresholds": {
        "mode": "absolute",
        "steps": [
          {
            "color": "green",
            "value": null
          },
          {
            "color": "#EAB839",
            "value": 0.1
          },
          {
            "color": "#6ED0E0",
            "value": 0.2
          }
        ]
      },
      "mappings": []
    },
    "overrides": []
  },
  "options": {
    "mergeValues": true,
    "showValue": "auto",
    "alignValue": "left",
    "rowHeight": 0.9,
    "legend": {
      "displayMode": "list",
      "placement": "bottom"
    },
    "tooltip": {
      "mode": "single"
    }
  },
  "targets": [
    {
      "expr": "rate({job=\"tns/db\"}[$__interval])",
      "legendFormat": "A",
      "refId": "A"
    },
    {
      "expr": "rate({job=\"monitoring/node_exporter\"}[$__interval])",
      "hide": false,
      "legendFormat": "B",
      "refId": "B"
    }
  ]
}