[RBAC] syncing of repository with a remote requires specifying a remote at sync time

[dkliban]

Version
3.43 and probably earlier

Describe the bug
I have a user that has the permissions to create repositories and remotes. The user created a remote and then created a repository with that remote associated. When the user tries to sync the following error is produced:

Error: {"remote":["This field is required since a remote is not set on the repository."]}

To Reproduce

1. Create a user that can create rpm remotes and rpm repositories.
2. pulp rpm remote create --url https://fixtures.pulpproject.org/rpm-alt-layout/ --name rpmfoo
3. pulp rpm repository create --name rpmfoo --remote rpmfoo
4. pulp rpm repository sync --name rpmfoo

Additional context
The problem seems to be that the self.context[0] does not have repository_pk when a non-admin user is performing the request.

Domains are enabled on this Pulp instance.

[0] https://github.com/pulp/pulpcore/blob/3.43/pulpcore/app/serializers/repository.py#L346