[fluentd-elasticsearch] Remove deprecated "kubernetes.io/cluster-service" label

[eric-herve]

Is this a BUG REPORT or FEATURE REQUEST? :
FEATURE REQUEST

Version of Helm and Kubernetes:
Helm v3.1.2 and Kubernetes v1.15.9

Which chart in which version:
9.0.0

What happened:
In my CI, I play the result of "helm template" command with "kubectl diff" command to have a finer result (and closer to reality) than with a "helm diff".
The command "helm template" leaves manifests WITH the label "kubernetes.io/cluster-service".
The command "helm upgrade" plays the manifests WITHOUT the label "kubernetes.io/cluster-service" (because this label is deprecated or because helm upgrade does not use .Capabilities.KubeVersion.GitVersion).
As soon as I make a "kubectl diff" with the result of the "helm template", this label is systematically missing and sees a diff.

if semverCompare "> 1.6" .Capabilities.KubeVersion.GitVersion
	kubernetes.io/cluster-service: "true"
end

Could you please remove this label ?