Changes proposed in this Pull Request

When option simpl is set, an error is raised due to mismatch on symbol when applying get_clustering_from_busmap. This is due to the fact that the given busmap raise an error in consense aggregation function.

It should not be an issue because symbol column is dropped later on in the script. This is why this PR suggest to invert the order of cluster function and the drop of unused columns.

Fix following raised error in simplify_network :

AssertionError: In Bus cluster symbol, the values of attribute symbol do not agree

Relates with : https://groups.google.com/g/pypsa/c/HkKBySQFrK8

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.
• A release note doc/release_notes.rst is added.