[frontend] expect the correct status code for project deletion failure
    
    The c2fcfff for some reason changed the expected status code for a
    failed request to remove project (because of unfinished builds in it).
    Seems to me like the assert was changed to just comply with a bugged
    frontend behavior. Or maybe those two bugs negated each other.
    
    However, once I've fixed the issue with wrong `finished` status for
    SRPM builds in ab70329, then this test started failing.