add deploymentlabel to user-deployment (#25981)

## Summary & Motivation
In our organization we need to add labels to deployments for internal
quality checks. Currently it is seems only possible to set labels on pod
level via values.
I want to set the labels on the deployment according to the ones set in
the pods of the respective deployment.

![rancher_screenshot](https://github.com/user-attachments/assets/b4fb2ec1-e259-443d-a9a9-737901b351ea)

## How I Tested These Changes
Successfully applied changes via terraform locally resulting in set
labels for deployment

helm/dagster/charts/dagster-user-deployments/templates/deployment-user.yaml

@@ -8,6 +8,9 @@ metadata:
     {{- include "dagster.labels" $ | nindent 4 }}
     component: user-deployments
     deployment: {{ $deployment.name }}
+    {{- with $deployment.labels }}
+    {{- . | toYaml | nindent 4 }}
+    {{- end }}
   annotations: {{ $deployment.annotations | toYaml | nindent 4 }}
 spec:
   replicas: 1