Replace or remove over_the_counter_health_expenses as a hard target

[MaxGhenis]

over_the_counter_health_expenses is currently calibrated using a Consumer Expenditure Survey benchmark. If we keep this target, it should be replaced with a broader official macro proxy or removed.

Why the current target is weak:

• CE is survey-based.
• CMS NHEA has a broader official category for non-prescription drugs and medical sundries (other non-durable medical products).
• Even that NHEA category is not a pure administrative total and is broader than the current model variable, so this may be better handled as a diagnostic or removed entirely.

Proposed change:

• Either replace over_the_counter_health_expenses with an explicitly documented NHEA other non-durable medical products proxy, or remove it from the hard calibration target set.

Primary sources:

• CMS National Health Expenditure Data: https://www.cms.gov/data-research/statistics-trends-and-reports/national-health-expenditure-data
• CMS NHEA definitions, sources, and methods: https://www.cms.gov/files/document/definitions-sources-methods.pdf
• BLS Consumer Expenditure Survey: https://www.bls.gov/cex/