Flight plan deletion status is too strict in cleanup phase

[BenjaminPelletier]

Observed behavior
When cleaning up, uss_qualifier fails a check when a USS responds with NotPlanned to a flight deletion request rather than Closed. If we knew the flight was actually created (as is usually the case in the main body of a test scenario), this would probably be a legitimate failure. However, in cleanup we simply want the flight to be gone and don't care much about semantics apart from that. In the particular case I observed, however, uss_qualifier did not know the flight was actually created, and in fact could have reasonably inferred that it was not created. In that case, NotPlanned is a perfectly valid response (probably more valid than Closed), but the check still failed -- see s303e28.

s303.html

Test check
Successful flight deletion

Difference from expected behavior
The check should certainly not fail when a USS responds NotPlanned to a deletion request for a flight that might not exist, and probably shouldn't fail regardless of {NotPlanned, Closed} in any situation since this is merely cleanup.

We should hopefully fix this wherever it occurs across similar scenarios as well.

[the-glu]

"The check should certainly not fail when a USS responds NotPlanned to a deletion request" should be fixed by #1403 and "probably shouldn't fail regardless of {NotPlanned, Closed} in any situation since this is merely cleanup" should be fixed by #1404