vim:coc: Decrease message delay

The value of 25 is orientated at my key repeat rate of 50 (see xinitrc).
This way the message comes fairly quick while not refreshing on every
character when keeping a navigation key pressed.

.config/vim/coc-settings.json

@@ -1,3 +1,4 @@
 {
+	"diagnostic.messageDelay": 25,
 	"inlayHint.enable": false
 }