`load_service_config` does not apply environment variables for overrides

[OjusWiZard]

Subject of the issue

We use load_service_config to load the service config in Pearl, but this function doesn't apply environment variables for the overrides. It says in a comment:

    # Here we apply the environment variables to base service config only
    # We apply the environment variables to the overrides when processing
    # them to export as environment variables

Not sure why that's the case, but I expected it to load and process it entirely.

Your environment

• OS: Debian linux
• Python version: 3.10.12
• Package Version 0.18.2
• Anything else you consider helpful.

Steps to reproduce

Just call load_service_config and pass the path to a service containing service.yaml

Expected behaviour

the returned service instance should have the environment variables assigned in the .overrides, or the default values.

Actual behaviour

They are not assigned, but the same as written in the config file.