test: add a bunch of libinput_dispatch() before timeout calls

test: add a bunch of libinput_dispatch() before timeout calls

98346f6a1aa added a warning about timeouts expiring before now. Those warnings
are triggered by a bunch of tests where we have events, then a timeout, then a
libinput_dispatch().

All these are bugs in the test, since we can't guarantee the order of fds (and
thus which fd the events are pulled off first) it's just lucky that they worked.
Insert the required libinput_dispatch() calls.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Jonas Ådahl <jadahl@gmail.com>