Operating system

Ubuntu 22.04.5 LTS

Helmfile Version

v1.2.1, v1.2.2, v1.2.3

Helm Version

v3.19.4

Bug description

We use helmfile in a "module" approach and have had some unexpected array merging issues since helmfile v1.2.1 which might be related to #2281. With this "new" merging mechanism, it is not possible anymore to overwrite (https://helmfile.readthedocs.io/en/latest/writing-helmfile/#merging-arrays-in-layers) a list from the outside. We would prefer to change the "merging way" back as it used to be in helmfile v1.2.0.

Example helmfile.yaml

As seen in the provided examples (01-06), only one behaves as expected and as in helmfile v1.2.0. 
Please see the following example structure. The different "tests" can be run with helmfile template --file examples/01/helmfile.yaml.
The expected result and the actual results are described in the helmfile.yaml of the corresponding example.

https://github.com/pgmgb/helmfile-list-merg-issue

.
├── README.md
├── examples
│   ├── 01
│   │   └── helmfile.yaml
│   ├── 02
│   │   └── helmfile.yaml
│   ├── 03
│   │   └── helmfile.yaml
│   ├── 04
│   │   └── helmfile.yaml
│   ├── 05
│   │   └── helmfile.yaml
│   └── 06
│       └── helmfile.yaml
├── helmfile.yaml
├── releases
│   └── list
│       └── list.yaml.gotmpl
└── values.yaml

Error message you've seen (if any)

See "Example helmfile.yaml"

Steps to reproduce

See "Example helmfile.yaml"

Working Helmfile Version

v1.2.0

Relevant discussion

No response