fix: remove if-wrappers from error flags

[toddbaert]

The if wrappers were added in #356 (my bad), but json-logic's if coerces its condition to a boolean; null and false are both falsy, so the if always selects the "false" variant for both cases. This makes it impossible to verify that operators return null (not false) on error, which is the entire point of the @operator-errors scenarios.

By using the operator directly as the top-level targeting expression, a null return propagates to the evaluator, which falls back to defaultVariant with reason DEFAULT; a false return would resolve to the "false" variant with reason TARGETING_MATCH. The distinction is preserved.

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I tested this locally and with this and the expected fixes, I was able to get the test suite fully updated in in-process mode! No more inconsistencies!

[gemini-code-assist]

Code Review

This pull request refactors the flag configuration files by simplifying the targeting logic, specifically removing redundant 'if' wrappers and directly defining conditions like 'sem_ver', 'fractional', and string operators. It also updates the variants for fractional flags to better match their bucket configurations. I have no feedback to provide.