unit-test-app: disable encrypted flash read/write in psram config to fix build failure

tools/unit-test-app/configs/psram

@@ -3,3 +3,5 @@ CONFIG_ESP32_SPIRAM_SUPPORT=y
 CONFIG_ESP_INT_WDT_TIMEOUT_MS=800
 CONFIG_SPIRAM_OCCUPY_NO_HOST=y
 CONFIG_ESP32_WIFI_RX_IRAM_OPT=n
+# Disable encrypted flash reads/writes to save IRAM in this build configuration
+CONFIG_SPI_FLASH_ENABLE_ENCRYPTED_READ_WRITE=n