This patch reworks the Pod rolling mechanism, which is supposed to update Pods
with each migration run, but since the it generates a new random value on each
helm execution, this will constantly roll all pods in a GitOps driven deployment,
which reconciles the helm release.

This is resolved by fixing the upgrade to the `.Release.Revision`, which should
stay identical, unless config or helm release version have been changed. Further
it introduces automatic rolls based on adjustments to the environment variables
and secrets.

The implementation uses a helper template, following the 1-2-N rule, and omitting
code duplication.

References:
https://helm.sh/docs/chart_template_guide/builtin_objects/
https://helm.sh/docs/howto/charts_tips_and_tricks/#automatically-roll-deployments