Fix typo (#5413)

# What this PR does
fix typo

## Which issue(s) this PR closes

Related to [issue link here]

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## Checklist

- [ ] Unit, integration, and e2e (if applicable) tests updated
- [x] Documentation added (or `pr:no public docs` PR label added if not
required)
- [x] Added the relevant release notes label (see labels prefixed w/
`release:`). These labels dictate how your PR will
    show up in the autogenerated release notes.

engine/apps/alerts/constants.py

@@ -28,4 +28,4 @@ class AlertGroupState(str, Enum):
 
 
 SERVICE_LABEL = "service_name"
-SERVICE_LABEL_TEMPLATE_FOR_ALERTING_INTEGRATION = "{{ payload.common_labels.service_name }}"
+SERVICE_LABEL_TEMPLATE_FOR_ALERTING_INTEGRATION = "{{ payload.commonLabels.service_name }}"