Fix usage of compare_list_reduced variable

[Rickmarges]

What does this PR do?

The object diff plugin used the wrong variable in 1 place when using with_present.
When using that option, the state: present key is added to the compare_list_reduced dict, however, the compare_list was then extended and returned.

This also solves removing too much differences based on the if-statement on line 332 as less dict now have less than 3 keys

How should this be tested?

Manual

1. Create list of roles to configure (for example: {"controller_roles": [{"team": "dummy", "job_template": "dummy_template", "role": "read"}]
2. Run the diff role with include_present_state: true
3. The diff output now actually contains the state: present key. Before it did not

Is there a relevant Issue open for this?

Other Relevant info, PRs, etc

[ivarmu]

LGTM

[sean-m-sullivan]

Sorry this took a bit for me to get to and review wanted to test and step through it, thanks!