add small nightly AMIP ensemble

[juliasloan25]

It would be helpful to discover incompatibilities in upstream packages as early as possible. Our current system of regular CI + weekly longruns is helpful, but depends on how frequently we release and update for the upstream packages. In an effort to stay on top of behavior and breaking changes, we want to set up a nightly AMIP run that uses the main branch of important upstream packages, including:

• ClimaAtmos
• ClimaLand
• ClimaCore
• Thermodynamics
• SurfaceFluxes
• RRTMGP

The goal for these runs is to be very fast (ideally ~12 hours), so they will be very coarse resolution. We also want to account for nondeterminism/variance between the runs, so we'll run a small ensemble of 4-6 simulations.