Demote or replace health_insurance_premiums_without_medicare_part_b as a hard target

[MaxGhenis]

health_insurance_premiums_without_medicare_part_b is currently treated as a hard calibration target, but there is no clean administrative national total for household premium outlays excluding Medicare Part B.

Why the current target is weak:

• The current benchmark is MEPS/NHEA-based, which is better than CPS but still not a clean administrative total.
• CMS NHEA is the best official macro source here, but it is an account series assembled from mixed inputs and residual methods, not a one-to-one administrative measure of this exact concept.
• That makes it a weak hard target if we are trying to keep the calibration set admin-first.

Proposed change:

• Demote health_insurance_premiums_without_medicare_part_b from a hard calibration target.
• If we want to retain a consistency check, define an explicit NHEA-based soft benchmark and document the concept mismatch.
• Keep medicare_part_b_premiums as the clean admin-backed target.

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
• CMS MEPS reconciliation note: https://www.cms.gov/data-research/statistics-trends-and-reports/national-health-expenditure-data/meps-reconciliation