maps: add some sleeps to the zoom test
    
    These loops make us click extremely fast. This may cause
    unreliable results, I think. At least, the test is failing a
    lot lately, with results that look like it's not always getting
    the expected four levels of zoom. Let's try a short sleep
    between clicks.
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>