Allow overriding the Label in podTemplate when using agent/additionalagents

[asaphe]

Is your feature request related to a problem? Please describe

The issue is that when you specify podLabels it is not used by Jenkins itself and you cannot refer to it in a pipeline. using customJenkinsLabels just appends the labels and doesn't set them.

The default is - label: "{{ .Release.Name }}-{{ .Values.agent.componentName }} {{ .Values.agent.customJenkinsLabels | join " " }}"

this is an issue as it forces us to use very this very long name in a pipeline. the way to workaround this is to use podTemplate instead.

Describe the solution you'd like

It would be great if we could simply override this extremely long label.

Describe alternatives you've considered

using podTemplate but that is a bit more convuluted than the very simple additional agents.

Additional context

No response