Fixes #29122 - Correct CV deletion behavior for pulp3

[jlsherrill]

This fixes four situations:

• Deleting a CVV would delete the pulp3 repository, deleting repo
  versions across all CVVs in that content view
• Deleting a CV would NOT delete the pulp3 repository, when it should
• Removing a CVV from a Lifecycle Env would not properly delete the
  distribution
• If you deleted a CVV, that had re-used the version_href and
  publication_href from a Library repo, it would delete the library
  repo's pulp3 repo version (and thus its publication too).

[theforeman-bot]

Issues: #29122

[jlsherrill]

TODO:

• - add more testing

Testing scenarios:

I'd recommend running this query to get a good idea of what is in pulp3 and what gets deleted:

sudo -u postgres psql pulpcore


select (select count(*) as repos from core_repository ), (select count(*) as repo_versions from core_repositoryversion), (select count(*) as publications from core_publication), (select count(*) as distributions from core_basedistribution);

1. Create a file repository in library. Counts:

 repos | repo_versions | publications | distributions 
-------+---------------+--------------+---------------
     1 |             1 |            1 |             1

2. Create a content view, add the file repository, and publish

 repos | repo_versions | publications | distributions 
-------+---------------+--------------+---------------
     2 |             2 |            1 |             2

3. Remove the CVV from the library lifecycle env

 repos | repo_versions | publications | distributions 
-------+---------------+--------------+---------------
     2 |             2 |            1 |             1

4. Remove the 1.0 CVV altogether:

 repos | repo_versions | publications | distributions 
-------+---------------+--------------+---------------
     2 |             2 |            1 |             1

5. Delete the CV:

 repos | repo_versions | publications | distributions 
-------+---------------+--------------+---------------
     1 |             1 |            1 |             1

[jjeffers]

Worked as described, but I did have a question re the force_pulp3 parameter...

[jjeffers]

When would we use the force_pulp3 parameter?

[jlsherrill]

Its used in one place at the moment. When we delete a content view: https://github.com/Katello/katello/pull/8594/files#diff-d4b12ef3369bd829bf21911a41392ee5R17

If at this point we aren't using pulp3 for that type of content, but for some reason a Pulp3::RepositoryReference exists, it means we have to have run the content migration already, but are deleting stuff before actually switching over to pulp3. So it makes sense to force it in order to get the backend service object to delete the pulp3 repository.