Fix Grafana's data source config for pgsql (#666)

### Checklist

- [x] Follow the [manual testing
process](https://github.com/sourcegraph/deploy-sourcegraph-helm/blob/main/TEST.md)
- [ ] Update
[changelog](https://github.com/sourcegraph/deploy-sourcegraph-helm/blob/main/charts/sourcegraph/CHANGELOG.md)
- [ ] Update [Kubernetes update
doc](https://docs.sourcegraph.com/admin/updates/kubernetes)

### Test plan

Tested on self-hosted instance

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Author: marcleblanc2

charts/sourcegraph/templates/grafana/grafana.ConfigMap.yaml

@@ -16,14 +16,15 @@ data:
         access: proxy
         url: http://{{ default "jaeger-query" .Values.jaeger.query.name }}:16686/-/debug/jaeger
       - name: pgsql
-        type: postgres
-        url: $GRAFANA_PGSQL_HOST:$GRAFANA_PGSQL_PORT
-        user: $GRAFANA_PGSQL_USER
         database: $GRAFANA_PGSQL_DATABASE
-        secureJsonData:
-          password: $GRAFANA_PGSQL_PASSWORD
+        editable: true
         jsonData:
           sslmode: $GRAFANA_PGSQL_SSLMODE
+        secureJsonData:
+          password: $GRAFANA_PGSQL_PASSWORD
+        type: postgres
+        url: $GRAFANA_PGSQL_HOST:$GRAFANA_PGSQL_PORT
+        user: $GRAFANA_PGSQL_USER
 kind: ConfigMap
 metadata:
   labels: