Rename taxsim validation test files to indicate they're not unit tests

Currently many test files named after variables (our convention for unit tests) have more inputs than those immediately used in the variable's formula, as they validate against taxsim and came from scripts that generated many test cases. For example, see the state-level tests modified in https://github.com/PolicyEngine/policyengine-us/pull/5582. Let's rename these to indicate they're integration tests.