chart: add scheduler and controller-manager prometheus scrape annotations

[7sunarni]

From the values.yaml, the both of controller-manager and scheduler components are enabled metrics by default.
I think we should add some default Prometheus annotations, so the metrics data can be scraped when we install by helm.

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[7sunarni]

BTW, I found that the chart forget to clear the admission secret after uninstall it. I add a new commit to fix this.