Fix for simulation-based shadow pricing segmentation

[i-am-sijia]

Addressing #1082 with option 2 ...

Summary generated by Copilot (reviewed):

This pull request refactors how chooser segments are handled in the shadow pricing logic, making the configuration more flexible and robust. It uses CHOOSER_SEGMENT_COLUMN_NAME from the location choice model setting for chooser segmentation to keep shadow-pricing resampling consistent with segment_ids in location choice settings, adds better error handling for misconfigurations, and introduces new tests to cover these scenarios.

Shadow Pricing Configuration Improvements:

• Removed the hardcoded SEGMENT_TO_NAME mapping from both the module-level dictionary and the ShadowPriceSettings class.
• The ShadowPriceCalculator now uses the CHOOSER_SEGMENT_COLUMN_NAME from location choice model settings to determine the chooser segment column dynamically.

Error Handling Enhancements:

• In update_shadow_prices, added explicit checks to raise a SystemConfigurationError if the configured chooser segment column is missing from persons_merged, or if there is no overlap between SEGMENT_IDS values and the values present in the chooser segment column.

Testing Improvements:

• Added new unit tests to verify that shadow pricing works with customized chooser segments (e.g., a string column) and that misconfigurations (such as non-overlapping segment values) are properly detected and raise clear errors.
• Updated test fixtures to include string-valued chooser segment columns for more comprehensive coverage.

[jpn--]

As discussed in engineering 8/27, this needs a unit test. @i-am-sijia will tackle this.