Revert "vfx: update BREATHING mode flush period"

This reverts commit 9ebd97b.

Author: redchenjs

main/src/user/vfx.c

@@ -928,7 +928,7 @@ static void vfx_task(void *pvParameter)
             uint16_t fade_cnt = 0;
             uint16_t color_h = esp_random() % 512;
             float color_l = vfx.lightness / 256.0;
-            const uint16_t flush_period = 10;
+            const uint16_t flush_period = 8;
 
             while (1) {
                 xLastWakeTime = xTaskGetTickCount();