tests: Don't wait for frame callbacks when a surface is on no outputs

The event-test moves a client off of all the outputs to check for an output leave event, but our move_client() code waits on a frame callback to continue.

The fact that weston currently generates this frame callback is not something we should enforce in a test, as it could (should) change in the future.

Signed-off-by: Derek Foreman derek.foreman@collabora.com