[24.1] Fix very slow workflow editor loading

[mvdbeek]

Loading the editor for my usegalaxy.org account takes 20 seconds. I've narrowed this down to the unnecessary join against the workflow table and loading all steps. I'm also returning the needed columns directly.
The query is still about 1 second if the database cache is not hot (on consecutive execution the query finishes in ~ 7ms) with no obvious room for improvement (except for composite index), but I think with #18729 we might not have to load up the full list of workflows and step counts ahead of time anymore.

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.