Try to make tmux-transient-prompt.fish more consistent

Author: kerty0

tests/checks/tmux-transient-prompt.fish

@@ -26,8 +26,9 @@ isolated-tmux send-keys C-u '
     function fish_prompt
         printf "\$ "
     end
-' C-l
-isolated-tmux send-keys Enter Enter
+'
+tmux-sleep
+isolated-tmux send-keys C-l Enter Enter
 tmux-sleep
 isolated-tmux capture-pane -p
 # CHECK: $
@@ -43,8 +44,9 @@ isolated-tmux send-keys C-u C-l '
             printf "transient line%d\n" 1 2
         end
     end
-' C-l
-isolated-tmux send-keys Enter
+'
+tmux-sleep
+isolated-tmux send-keys C-l Enter
 tmux-sleep
 isolated-tmux capture-pane -p
 # CHECK: final line1
@@ -63,8 +65,9 @@ isolated-tmux send-keys C-u C-l '
             echo "1> "
         end
     end
-' C-l
-isolated-tmux send-keys 'echo foo' Enter
+'
+tmux-sleep
+isolated-tmux send-keys C-l 'echo foo' Enter
 tmux-sleep
 isolated-tmux capture-pane -p
 # CHECK: 2> echo foo
@@ -76,7 +79,7 @@ isolated-tmux capture-pane -p
 # final.
 isolated-tmux send-keys C-u C-l
 isolated-tmux send-keys 'echo foo \\' Enter
-isolated-tmux send-keys 'bar' Enter
+isolated-tmux send-keys bar Enter
 tmux-sleep
 isolated-tmux capture-pane -p
 # CHECK: 2> echo foo \