Remove deprecated configuration options

[bouweandela]

Description

Remove various deprecated configuration modules and methods:

• esmvalcore.experimental.config -> to upgrade, import the module from esmvalcore.config
• esmvalcore._config -> to upgrade, use esmvalcore.config instead
• esmvalcore.config.Session.to_config_user and esmvalcore.config.from_config_user -> to upgrade, use esmvalcore.config.Session to access the configuration values instead of a separate dict

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[codecov]

Codecov Report

Merging #2056 (d96be5a) into main (64f7c0f) will increase coverage by 0.07%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #2056      +/-   ##
==========================================
+ Coverage   92.79%   92.87%   +0.07%     
==========================================
  Files         236      234       -2     
  Lines       12484    12441      -43     
==========================================
- Hits        11585    11554      -31     
+ Misses        899      887      -12     

Impacted Files	Coverage Δ
esmvalcore/config/_config_object.py	94.95% <ø> (+7.37%)	⬆️

[valeriupredoi]

thanks bud, these slated to be removed in 2.9 right?

[valeriupredoi]

@schlunma maybe you got a couple seconds have a last look at this then merge, pls. bud 🍺

[schlunma]

Thanks @bouweandela for taking care of this!

It seems that one of these functions is still used in ESMValTool: https://github.com/ESMValGroup/ESMValTool/blob/main/tests/system/data_simulator.py#L10

Could you either open an issue or PR to address this, please? Thanks!!

[valeriupredoi]

done! Am on a roll today 😁 ESMValGroup/ESMValTool#3195

[bouweandela]

Could you either open an issue or PR to address this, please? Thanks!!

See ESMValGroup/ESMValTool#3109

[valeriupredoi]

Bouwe needs to read comments more often and I need to check for existing issues 🤣