This reverts merge request !20801

This is refactoring in the lead up to passing mutual TLS certs for helm applications. As such we expect all applications to need config files so we can remove the logic about which applications need and do not need this (ie `#config_map?`).

Backports relevant changes made in https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/5163 to CE

Closes #48978

This was causing a spec failure between Gitlab::Kubernetes::Helm::Pod and
Gitlab::Kubernetes::Helm::Api::Pod if one spec loaded the former
definition first.

Closes #41458

Ensure `Namespace`'s is namespaced in `Gitlab::Kubernetes::Helm#initialize` and fix a transient failing spec due to that

Signed-off-by: Rémy Coutable <remy@rymai.me>

Adds a rubocop rule (with autocorrect) to ensure line break after guard clauses.