ci(sdspi): clean up newlib memory, reset between tests

Two changes to make the tests less susceptible to random failures:
- Free up newlib memory to not have false-positive memory leaks due to
  lazy allocations in reent structure
- Reset between tests, so that one failing test doesn't cause
  subsequent tests to fail

Both changes are already applied to esp_driver_sdmmc test app.

components/esp_driver_sdspi/test_apps/sdspi/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);
 }
 

components/esp_driver_sdspi/test_apps/sdspi/pytest_sdspi.py

@@ -1,8 +1,7 @@
 # SPDX-FileCopyrightText: 2022-2023 Espressif Systems (Shanghai) CO LTD
 # SPDX-License-Identifier: CC0-1.0
-
 from pytest_embedded_idf import IdfDut
 
 
 def test_sdspi(dut: IdfDut) -> None:
-    dut.run_all_single_board_cases()
+    dut.run_all_single_board_cases(reset=True)