Limit gb-model to clustered scenario

[brynpickering]

Based on internal discussion, this PR limits the GB model to clustered only, simplifying rules to not mention clustered in filenames unnecessarily. We have to keep the wildcard in compose_network so that input_profile_tech gets the appropriate wildcard entry, but I've constrained the wildcard option to just clustered.

Checklist

• I tested my contribution locally and it works as intended.
• Code and workflow changes are sufficiently documented.
• Changed dependencies are added to envs/environment.yaml.
• Changes in configuration options are added in config/config.GB.yaml.
• Changes in configuration options are documented in doc/gb-model/configtables/*.csv.
• OET SPDX license header added to all touched files.
• Sources of newly added data are documented in doc/gb-model/data_sources.rst.
• A release note doc/gb-model/release_notes.rst is added.

[yerbol-akhmetov]

Hi, @brynpickering. Thank you for the PR. I have tested it locally. It works fine, though there is issue with load_costs in compose_network. It is due to recent merge from upstream. Now load_costs does not take arguements, but loads processed costs. But it is not related to this PR at all.