This commit does three things:
1. Breaks the inheritance of the VariantQuery.
2. Revisits the in-line documentation to better reflect current state.
3. Removes branching logic that we don't need.
My goal is to have a VariantQuery that is what we need, conforms to the
method interface of WeightedQueryStrategy but does not rely on it.
After we merge this, we can observe if things break on DEV and fallback
to WeightedQueryStrategy if this doesn't work. Once the
`Articles::Feeds::VariantQuery` has fledged on it's own, we can remove
the feature flag and then finally remove the weighted query strategy.
But that's the future steps.
Related to forem/forem#17393
8b37e3aca9