feat(dashboard): nullify hardcoded id

[weisdd]

When id is hardcoded in a GrafanaDashboard, the operator is likely to fail to create the dashboard in a Grafana instance.
The PR makes sure id is nullified before dashboard model is passed to Grafana client.

(Strictly speaking, id should never be defined by a user in the first place, so it's more around improving UX.)

More details

Basically, when id is set, Grafana tries to update a dashboard by the id, not uid. And, expectedly, that can cause various issues, e.g. if the id is not known to Grafana, Grafana responds with 404.

Example of a failing CR

apiVersion: grafana.integreatly.org/v1beta1
kind: GrafanaDashboard
metadata:
  name: grafanadashboard-sample
spec:
  resyncPeriod: 30s
  instanceSelector:
    matchLabels:
      dashboards: "grafana"
  json: >
    {
      "id": 146,
      "title": "Simple Dashboard",
      "tags": [],
      "style": "dark",
      "timezone": "browser",
      "editable": true,
      "hideControls": false,
      "graphTooltip": 1,
      "panels": [],
      "time": {
        "from": "now-6h",
        "to": "now"
      },
      "timepicker": {
        "time_options": [],
        "refresh_intervals": []
      },
      "templating": {
        "list": []
      },
      "annotations": {
        "list": []
      },
      "refresh": "5s",
      "schemaVersion": 17,
      "version": 0,
      "links": []
    }

Fixes: #1108

[NissesSenap]

Sounds very reasonable to me. LGTM

[owenhaynes]

Will there be a patch release soon for this fix? Currently looking to migrate form v4 -> v5 and this is a little bit of regression. I know v5 is a major release. Its just a shame Grafana does not by default exclude this id when exporting dashboards.

[weisdd]

@owenhaynes it's now part of v5.0.2 that got released today :)