[TASK] Inject arbitrary configurations for existing resources into Helm Charts

[hisImminence]

Related to

PDP: https://github.com/camunda/product-hub/issues/2697
EPIC: https://github.com/camunda/team-distribution/issues/411

Overview

We already supported injecting extra manifests (#2999) via the values file. However, overriding what's already configured in the template is not really possible as it's against the whole idea of Helm as templating engine. So we will rely on the built-in feature of Helm post rendering.

Actions

• Document the ability to manipulate the manifests using Helm post rendering.

Tasks/PRs

• docs(self-managed): add section for helm manifests manipulation camunda-docs#6604

[aabouzaid]

Related request: #1815