search: mjolnir: fix query_clicks_ltr date argument order
Swapped --start-date and --end-date arguments to correctly reflect
the training window logic. --start-date now uses query_clicks_end_date,
and --end-date uses query_clicks_start_date, ensuring the proper
date range is applied.
Update mjolnir dep to 2.5.1 to deploy fixes implemented in repos/search-platform/mjolnir!13 (merged)
Bug: T360536