Improve handling of waivers for queued/running tests

[AdamWill]

A post from @rwmjones on devel highlighted some issues with waivers and queued/running tests:

https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org/thread/CAGORC7P56D66CTYIQ4PT2SO4GJHGEB2/

I'll have to verify this, but I believe that as things stand, the web UI will allow you to file waivers for required tests that are queued/running, but the greenwave gating status calculation does not take such waivers into account. Obviously that's inconsistent.

Personally I think it's correct that we don't allow queued/running tests to be waived. If we go with that, then the Bodhi web UI should not offer to file waivers for queued/running tests, only failed and possibly missing ones (I'll have to check if greenwave 'accepts' waivers for missing tests).

Also, if a waiver for a queued/running test somehow exists (e.g. someone creates it directly in waiverdb), it shouldn't be considered as 'applying', i.e. we shouldn't show the thumbs-up for it on the Automated Results tab. This overlaps somewhat with #5397 .

[AdamWill]

note: I found out today that waiving 'missing' results does work.

[AdamWill]

#5397 (comment) would partly address this by not showing running tests as waived even if a waiver is filed.