fixes #8355 - remove ambigious column plucks for older rails

Happens when listing errata for a content host on a production install on RHEL, due to the older version of Rails:

```
ActiveRecord::StatementInvalid: PGError: ERROR:  column reference "id" is ambiguous
LINE 1: SELECT id FROM "katello_errata" INNER JOIN "katello_reposito...
```

Foreman has dealt with a number of these issues too:
  https://github.com/theforeman/foreman/pulls?q=is%3Apr+pluck+is%3Aclosed