test: subsys: disable settings.tfm_its test for lpcxpresso55s69 ns.

For lpcxpresso55s69 TF-M, it has persistent storage available,
not applied for settings.tfm_its test.

Signed-off-by: Holt Sun <holt.sun@nxp.com>

Author: Holt-Sun

tests/subsys/settings/its/testcase.yaml

@@ -10,3 +10,5 @@ tests:
       - max32657evkit/max32657/ns
       - nrf5340dk/nrf5340/cpuapp/ns
       - nrf54l15dk/nrf54l15/cpuapp/ns
+    platform_exclude:
+      - lpcxpresso55s69/lpc55s69/cpu0/ns