More cleanup of tool shed tests.

[jmchilton]

More cleanup along the lines of https://github.com/galaxyproject/galaxy/pull/14662 - this time replacing repository abstraction used by test from the database model to the pydantic model fetched from the API.

The result is a better tested API, a more cohesive test that doesn't depend as much on tool shed internals, and more typing.

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

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