fix: remove obsolete checkup in solve_network.extra_functionality

[amos-schledorn]

Closes # (if applicable).
#1605

Changes proposed in this Pull Request

This PR removes an unnecessary if-clause in solve_network that can fail for electricity-only-networks and/or networks without links:

• When solving electricity-only systems, TES is enabled (default value) but heating bus not defined
• If network contains no links, if clause throws error

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.default.yaml.
• Changes in configuration options are documented in doc/configtables/*.csv.
• Sources of newly added data are documented in doc/data_sources.rst.
• A release note doc/release_notes.rst is added.

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Pull Request Overview

This PR removes an obsolete configuration check in the extra functionality of the solve_network script that raised an error when TES was enabled without a heating bus.

• Removed the error-raising if-clause that checked for "pits charger" or "tanks charger" strings in links and stores, which was causing issues in electricity-only networks and networks without links.

Comments suppressed due to low confidence (1)

scripts/solve_network.py:1182

• The removed conditional error check was guarding against misconfigured networks. Please ensure that the removal does not allow unsupported TES configurations to slip through unnoticed by updating or adding appropriate tests.

elif (n.links.index.str.contains("pits charger|tanks charger", case=False, na=False).any() or n.stores.index.str.contains("pits", case=False, na=False).any() or n.stores.index.str.contains("tanks", case=False, na=False).any()):