Remove julia conda package install and dependency

[valeriupredoi]

Description

Julia conda package is stuck at 1.10.4 which is an almost 9-month old version; they updated the base code to 1.10.8 https://github.com/JuliaLang/julia which includes a fix that permits us to free curl<8.10; freeing curl is becoming very important since that pin makes the env solving harder and harder, and holds back Python 3.13 too (not the only dep holding that though #3805 but an important one nonetheless); Julia conda feedstock appears to be rather abandoned https://github.com/conda-forge/julia-feedstock so am not sure how feasable and long term maintained it'll be to keep using the conda package; @bouweandela suggests we install Julia the "classic" way https://julialang.org/downloads/ so we can try that here

• Closes Unpin curl #3758 Unpin (and remove) curl #3807

TODOs

• understand why the Python<3.13 envs fail to solve -> NCL is making the env unsolvable after removing the curl<8.10 pin; with NCL removed, the env solves in 3 blithering minutes, fastest I've ever seen an ESMValTool env solve!
• pop the new-old installs of Julia and test with them

Dependencies that get modernized from removing curl pin

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