[nrf fromtree] tests: drivers: watchdog: wdt_basic_api: Run test on nrf54l15 NS

Enable wdt_basic_api test on nrf54l15dk/nrf54l15/cpuapp/ns platform.

Signed-off-by: Sebastian Głąb <sebastian.glab@nordicsemi.no>
(cherry picked from commit 80a00b8)

Author: nordic-segl

tests/drivers/watchdog/wdt_basic_api/boards/nrf54l15dk_nrf54l15_cpuapp_ns.overlay

@@ -0,0 +1,7 @@
+/*
+ * Copyright (c) 2025 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include "nrf54l15dk_nrf54l15_cpuapp.overlay"

tests/drivers/watchdog/wdt_basic_api/testcase.yaml

@@ -26,7 +26,6 @@ tests:
       - panb611evb/nrf54l15/cpuflpr
       - panb611evb/nrf54l15/cpuflpr/xip
       - mimxrt700_evk/mimxrt798s/cm33_cpu1
-      - nrf54l15dk/nrf54l15/cpuapp/ns
       - nrf54l15dk/nrf54l10/cpuapp/ns
       - nrf54lm20dk/nrf54lm20a/cpuapp/ns
       - bl54l15_dvk/nrf54l10/cpuapp/ns