ci(sdmmc): clean up stdout to avoid false positive memory leaks

components/esp_driver_sdmmc/test_apps/sdmmc/main/test_app_main.c

@@ -13,11 +13,13 @@
 
 void setUp(void)
 {
+    printf("%s", ""); /* sneakily lazy-allocate the reent structure for this test task */
     unity_utils_record_free_mem();
 }
 
 void tearDown(void)
 {
+    esp_reent_cleanup();
     unity_utils_evaluate_leaks_direct(TEST_MEMORY_LEAK_THRESHOLD);
 }