tests: initialize some variables
    
    Found by cppcheck:
    [tests/metadatatest.c:284]: (error) Uninitialized variable: test
    [tests/objecteventtest.c:855]: (error) Uninitialized variable: test
    
    Signed-off-by: Ján Tomko <jtomko@redhat.com>
    Reviewed-by: Jiri Denemark <jdenemar@redhat.com>