Docs: How-To section on configuring a high-throughput setup

[GeigerJ2]

As discussed with @giovannipizzi, this would be at least moving the "Tuning performance" section to this new HowTo. It would also mention tuning the safe_interval for SSH connection, once #6599 is merged. Pinging the team of people that have recently been looking into the docs on how to run with AiiDA, @npaulish, @mikibonacci, @mbercx, if you have some other input?