Do not try and add argo envs when disabled

[iameskild]

Reference Issues or PRs

Fixes #1904

What does this implement/fix?

Put a x in the boxes that apply

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds a feature)
• Breaking change (fix or feature that would cause existing features not to work as expected)
• Documentation Update
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no API changes)
• Build related changes
• Other (please describe):

Testing

• Did you test the pull request locally?
• Did you add new tests?

Any other comments?

[kenafoster]

I tested this with the following steps:

1. Starting with an existing Nebari deployment with no argo-workflows config specified (and therefore enabled by default), I confirmed JLab launches OK and includes argo vars
2. I updated my nebari config to disable argo workflows, deployed successfully, and confirmed launching JLab now fails, reproducing the error reported in the bug
3. Checked out branch fix-1904, re-ran nebari deploy successfully (same disabled workflows config), and now JLab launches successfully
4. Also in a JLab terminal, env | grep ARGO now shows nothing

[iameskild]

Thanks a bunch @kenafoster!!

@pavithraes @kcpevey could you please review and approve when you get a chance? Thank you

[pavithraes]

Thank you, @iameskild and @kenafoster! ✨