The `gardener-resource-manager` now features an optional garbage collector controller (disabled by default) for immutable `ConfigMap`s/`Secret`s. Please take a look at [this document](https://github.com/gardener/gardener-resource-manager/blob/master/docs/concepts/garbagecollector.md) if you want to use it.
How to categorize this PR?
/area robustness /kind enhancement
What this PR does / why we need it: See https://github.com/gardener/gardener-resource-manager/issues/104#issuecomment-879153687 and https://github.com/rfranzke/gardener-resource-manager/blob/enh/immutable/docs/concepts/garbagecollector.md.
Which issue(s) this PR fixes: Fixes #104
/squash
Release note: