Train the store's learned scoring function

Queue a learned-scoring-function training run for a store.

The store must have been created with config.lsf. The run collects signals for the store's captured searches and trains new weights when enough signalled elements exist, exactly like the scheduled daily run.

Args: store_identifier: The ID or name of the store.

Returns: StoreLsfTrainingQueued: Confirmation that the run was queued.