Correct domestic gas trade filtering

[trevorb1]

Changes proposed in this Pull Request

In this PR I update the natural gas filtering to match updated introduced in PR #453. This update removes the need for specific gas trade buses for states withing the geographic scope.

Checklist

• I tested my contribution locally and it seems to work fine.
• Code and workflow changes are sufficiently documented.
• Changed dependencies are added to envs/environment.yaml.
• Changes in configuration options are added in all of config.default.yaml.
• Changes in configuration options are also documented in doc/configtables/*.csv.