Tests: drop all modular tests but one to verify we get no event
    
    We stopped doing modular events again, but I forgot to update
    the tests. Drop all the tests but one, which we now use to
    ensure we don't create an event when a modular compose happens.
    We can always restore this again if necessary.
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>