Update Longruns

[LenkaNovak]

Purpose

We need to revamp our longruns to reflect the current requirements and capabilities of ClimaAtmos.

To-do

• adapt the pipeline.yml

QA

• show physically reasonable long runs
  
• perf: 10h15m for n=64, compared to standalone ClimaAtmos 23h for 400d but with n=64 https://buildkite.com/clima/climaatmos-longruns/builds/1098#_
  • note: n64 v n32 not a huge speed up: https://buildkite.com/clima/climacoupler-longruns/builds/199
  • note also - different timesteps