[23.0] Don't always install node in the virtualenv

[nsoranzo]

if it's already installed system-wide at the correct version.

Prevent node installation issues during CI builds where we install node with the setup-node action but it was ignored because it was not inside the virtualenv, e.g.:

https://github.com/galaxyproject/galaxy/actions/runs/5530959878/jobs/10091018774

How to test the changes?

(Select all options that apply)

• I've included appropriate automated tests.
• This is a refactoring of components with existing test coverage.
• Instructions for manual testing are as follows:
  1. [add testing steps and prerequisites here if you didn't write automated tests covering all your changes]

License

• I agree to license these and all my past contributions to the core galaxy codebase under the MIT license.