Update CMIP3 data entries in recipe to align with ESGF facets

[remi-kazeroni]

Is your feature request related to a problem? Please describe.
CMIP3 data entries in recipes are specified in a way that is only compatible with the DKRZ data pool. For example, in https://github.com/ESMValGroup/ESMValTool/blob/main/esmvaltool/recipes/bock20jgr/recipe_bock20jgr_fig_1-4.yml#L242-L249, we have:
exp: 20c3m, frequency: mo,
while the ESGF facets are:
exp: historical, frequency: mon.

It would be good to update the CMIP3 entries in our recipes so that missing data could be automatically downloaded at runtime. We would also need to update a few directory names on DKRZ so that these big IPCC recipes could still be tested on DKRZ-Levante.

Would you be able to help out?
Would you have the time and skills to implement the solution yourself?
Yes, I would suggest to tackle this for v2.9

[mo-gill]

Hi, we are currently working on the ESMValTool release for v2.11.0. We're wondering if you'd be able to finalise this issue by the end of next week (Friday 10th May).

Otherwise, please let us know, and we'll move it into the next milestone for you 🙂

[sloosvel]

Hi, the code freeze for version 2.12 will be on Monday 3rd of March. Is this ready to be included? If this is not ready, let me know and I will move it to the next milestone.