Documentation: Cookbooks with task codes, application upload_directory parameter left alone, deprecation notice for the unused $translator argument, scheduler log levels #216

Found by the global audit after the releases (bridges-audit.md §13):

• #62 Notify the end of the process executions with Symfony Notifier #133 Cookbooks form_file_upload.md, http_api_launch.md, scheduled_process.md: 11 tasks referenced by service: '@…' (deprecated by process-bundle 5.4) → task: <code>.
• /process/list and /process/launch accessed directly: 500 (no EasyAdmin context) #121 An application with its own upload_directory parameter (unrelated to the bundle, the collision which motivated Prefix the upload_directory parameter and the Twig functions and filter, deprecate the former names #196) gets the deprecation of the bundle and cannot silence it: when cleverage_ui_process.upload_directory is also set, leave upload_directory alone, and document it.
• #143 #144 - Stop a running process execution, detect the stale ones #146 The $translator argument of ProcessExecutionCrudController is deprecated without notice and without UPGRADE.md line: make it optional, trigger a deprecation when given (3.4), stop passing it.
• #138 - Document the Symfony Flex recipe #139 05-scheduler.md: a schedule that cannot be added is logged at the critical level, not info.