Remove "fx_variable" from recipe_wenzel14jgr.yml

[hb326]

Description

Remove the call to "fx_variables" in the recipe.

That change should take care of the the changes necessary for #3056

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Before you get started

• ☝ Create an issue to discuss what you are going to do

Checklist

New or updated recipe/diagnostic

• 🧪 Recipe runs successfully -> This recipe has some issues with running, but I thought I fix the call to the "fx_variables" anyway so that that is not the reason for the recipe to not run when we get around to fix it.
• 🧪 Recipe is well documented
• 🧪 Figure(s) and data look as expected from literature
• 🛠 Provenance information has been added

[schlunma]

@esmvalbot please run recipe_wenzel14jgr.yml

[esmvalbot]

Since @schlunma asked, ESMValBot will run recipe recipe_wenzel14jgr.yml as soon as possible, output will be generated here

[esmvalbot]

ESMValBot is sorry to report it failed to run recipe recipe_wenzel14jgr.yml: exit is null, output has been generated here

[remi-kazeroni]

Thanks @hb326! The recipe currently does not run for me but that is unrelated to this PR. I have opened a dedicated issue for that in #3224

@schlunma - I let you take a final look at this one and merge if ok for you 👍