Memcached replicas are not compatible with autoscaling

[friedrichg]

We need memcached chart to behave this way when autoscaling is enabled

cortex-helm-chart/templates/ingester/ingester-statefulset.yaml

Lines 13 to 15 in 706f190

	{{- if not .Values.ingester.autoscaling.enabled }}
	replicas: {{ .Values.ingester.replicas }}
	{{- end }}

[friedrichg]

I wouldn't recommend this gets fixed in bitnami helm charts. I think the opportunity is perfect to remove the upstream dependency.

Related to #548