Fix ignoring columns from has_one association for missing_unique_indexes

[fatkodima]

class User
  has_one :account
end

class Account
end

To disable missing_unique_indexes for checking unique index on accounts.user_id, we currently should add ignore_columns: ["User(user_id)"] to the config, which does not make sense. This PR fixes that so we should write as ignore_columns: ["Account(user_id)"].

[gregnavis]

@fatkodima, could you rebase the PR?

[fatkodima]

Rebased. Turns out, the code change is not needed now, only the test that is useful.

[gregnavis]

@fatkodima, interesting! Do you happen to know why the issue is gone now?

[gregnavis]

@fatkodima, the linter is failing.

[fatkodima]

This was fixed in b013fc0 🤷

Somehow this PR is a duplicate. We need to merge PRs faster 😅