tests/stacking: Avoid random failures in focus tests

Some tests were not waiting for the test client to actually issue
destroy commands before checking their effect on the window focus.

Similarly when mutter is supposed to change the focus based on a delay
by sending a WM_TAKE_FOCUS to the client, this also could fail without
synchronization with the client before checking the result.

https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1325

src/tests/stacking/closed-transient-no-input-parent-delayed-focus-default-cancelled.metatest

@@ -20,7 +20,7 @@ assert_focused 1/3
 assert_stacking 2/1 1/1 1/2 1/3
 
 destroy 1/3
-dispatch
+wait
 
 assert_focused none
 assert_stacking 2/1 1/1 1/2
@@ -32,5 +32,7 @@ assert_focused 2/1
 assert_stacking 1/1 1/2 2/1
 
 sleep 250
+wait
+
 assert_focused 2/1
 assert_stacking 1/1 1/2 2/1

src/tests/stacking/closed-transient-no-input-parent.metatest

@@ -20,11 +20,13 @@ assert_focused 1/3
 assert_stacking 2/1 1/1 1/2 1/3
 
 destroy 1/3
-dispatch
+wait
 
 assert_focused none
 assert_stacking 2/1 1/1 1/2
 
 sleep 150
+wait
+
 assert_focused 1/1
 assert_stacking 2/1 1/1 1/2

src/tests/stacking/closed-transient-no-input-parents-queued-default-focus-destroyed.metatest

@@ -30,14 +30,16 @@ assert_focused 1/5
 assert_stacking 0/1 1/1 1/2 1/3 1/4 1/5
 
 destroy 1/5
-dispatch
+wait
 
 assert_focused none
 assert_stacking 0/1 1/1 1/2 1/3 1/4
 
 destroy 1/2
-dispatch
+wait
 
 sleep 450
+wait
+
 assert_focused 1/1
 assert_stacking 0/1 1/1 1/3 1/4

src/tests/stacking/closed-transient-no-input-parents.metatest

@@ -30,12 +30,14 @@ assert_focused 1/5
 assert_stacking 0/1 1/1 1/2 1/3 1/4 1/5
 
 destroy 1/5
-dispatch
+wait
 
 assert_focused none
 assert_stacking 0/1 1/1 1/2 1/3 1/4
 
 sleep 600
+wait
+
 assert_focused 1/1
 assert_stacking 0/1 1/1 1/2 1/3 1/4
 

src/tests/stacking/closed-transient-only-take-focus-parents.metatest

@@ -30,5 +30,7 @@ assert_focused 1/2
 assert_stacking 0/1 1/1 1/2
 
 sleep 150
+wait
+
 assert_focused 1/2
 assert_stacking 0/1 1/1 1/2