Add relabelings to aws-load-balancer-controller Helm Chart servicemonitor template

**Is your feature request related to a problem?**
No

**Is your feature request related to a specific Helm chart, if yes mention name of the chart?**
aws-load-balancer-controller

**Describe the solution you'd like**
I'd like to enrich metrics with additional labels

In Helm Chart in metrics.yaml modify endpoints:

```
spec:
...
endpoints:
- port: metrics-server
path: /metrics
{{- with .Values.serviceMonitor.interval }}
interval: {{ . }}
{{- end }}
{{- if .Values.serviceMonitor.extraRelabelings }}
relabelings:
{{- toYaml .Values.serviceMonitor.extraRelabelings | nindent 6 }}
{{- end }}
```

**Describe alternatives you've considered**
No

Start with the Helm chart's metrics.yaml ServiceMonitor template and inspect the existing serviceMonitor values. Render the chart with serviceMonitor.extraRelabelings configured, then verify the generated ServiceMonitor endpoint contains the requested relabelings.

Written by the indexing model from the issue text.