[Fix-8804] Save actual status to cache

[hatkyinc2]

"Unsupported" status should be saved to cache, later to be used by total_correctable_count

This might resolve multiple reports on auto-correct for cops that don't have auto-correct on them

#8804
#8755

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Before submitting the PR make sure the following are checked:

• Wrote good commit messages.
• Commit message starts with [Fix #issue-number] (if the related issue exists).
• Feature branch is up-to-date with master (if not - rebase it).
• Squashed related commits together.
• Added tests.
• Added an entry to the Changelog if the new code introduces user-observable changes. See changelog entry format.
• The PR relates to only one subject with a clear title and description in grammatically correct, complete sentences.
• Run bundle exec rake default. It executes all tests and RuboCop for itself, and generates the documentation.

[hatkyinc2]

This seems to be the history of it..
d48304e

[bbatsov]

Don't forget to add some changelog entry for this and ideally a test or two.

[bbatsov]

Thanks!