DocumentSourceSearchMeta::createFromBson() has a few different paths of logic for handling cases like view definitions, non-sharded execution, and sharded execution with a merging pipeline. It also relies on a generic templated helper function createInitialSearchPipeline(), but that function is now only used in this one location. It's a bit tricky to understand the control flow, so we should clean that up and consider consolidating createInitialSearchPipeline() into the $searchMeta-specific logic.