Adjust to 'Final' milestone becoming 'RC' from Fedora 24 on
With Pungi 4 (Fedora 24+), the Final milestone more or less was
renamed to RC. Mostly let's allow both, but drop 'Final' from
report-results as no-one should be filing results on 23 or
earlier any more. Note that wikitcms will, as a kindness, change
Final to RC for 24+, so asking for '25 Final 1.1' will get you
25 RC 1.1.