Test #4838: [Epic] Test Distribution and AutoDistribution features from core
The PublicationDistribution is designed to be subclassed and can't be fully tested unless it is subclassed. Thus, the recommended way to test core's functionality is to test it using the FileDistributor from pulp_file.
CRUD the FileDistributor here: https://docs.pulpproject.org/en/3.0/nightly/restapi.html#operation/distributions_file_file_create
1. Create a repo and repo_version with at least 1 file content in it. Make a Publication from this repo_version
2. Create a PublicationDistribution with 'publication' field set to the publication from step (1)
3. Assert the Distribution got created correctly with the correct base_path, name, and publication. Leave content guard unset.
4. Assert that FilePublication has a 'distributions' reference to the Distribution (it's backref) https://docs.pulpproject.org/en/3.0/nightly/restapi.html#operation/publications_file_file_read