[24.2] Assertion linter fixes

[jmchilton]

Fixes #19705 - the old assertion linting was really poorly thought through. I think it was a fine idea but I wasn't passing the right things around in the right way. I think this is more closely models what happens at runtime and should ensure the validator code all runs properly at linting time.

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.