fix(unpoller): DPI dashboard (#28033)

Fixed DPI dashboard, it miss DS_PROMETHEUS variable

- [ ] ⚙️ Feature/App addition
- [x] 🪛 Bugfix
- [ ] ⚠️ Breaking change (fix or feature that would cause existing
functionality to not work as expected)
- [ ] 🔃 Refactor of current code

charts/stable/unpoller/Chart.yaml

@@ -34,4 +34,4 @@ sources:
   - https://github.com/truecharts/charts/tree/master/charts/stable/unpoller
   - https://github.com/unifi-poller/unifi-poller
 type: application
-version: 12.2.1
+version: 12.2.2

charts/stable/unpoller/dashboards/DPI.json

@@ -30381,6 +30381,13 @@
     "tags": ["unifi", "unifi-poller"],
     "templating": {
         "list": [
+            {
+                "hide": 2,
+                "name": "DS_PROMETHEUS",
+                "query": "Prometheus",
+                "skipUrlSync": false,
+                "type": "constant"
+            },
             {
                 "allValue": ".*",
                 "current": {},