Experimental feature: Limit the total size of batched tasks

[Kerollmops]

Feature name	How to enable	Description	Missing for stabilization
limit the total size of batched tasks	You can export the env variable, the command line argument, or the config file to limit Meilisearch to processing only a given number of tasks simultaneously. # You can either use this environment variable (100 MiB) MEILI_EXPERIMENTAL_LIMIT_BATCHED_TASKS_TOTAL_SIZE=104857600 # directly use this CLI argument (100 MiB) --experimental-limit-batched-tasks-total-size 104857600 # Or via the config file (100 MiB) experimental_limit_batched_tasks_total_size = 104857600	Reduces the total payload size of the batched tasks to reduce the RAM usage of the engine and reduce immediate latency	We could remove this flag and make the engine sufficiently good to choose the right number of tasks to process simultaneously depending on the kind of use case and workflow needed

How to use the feature?

1. Run Meilisearch with the environment variable or the command line argument flag described above
2. Profit.

Why is this feature not stable yet?

We are confident that this parameter will become useless in a short time. We are exposing this option to help the engine while we improve it. Once we make sure the engine is good enough to compute the limit of tasks it can auto-batch by itself, we will remove this parameter, and we don't want this to be a breaking change.

🗣️ You are welcome to give feedback about the score details or ask any question on its usage; we are eager to collect feedback on the feature