tests/kernel/fatal/exception: Skip stack sentinel test with shadow stack

Test could trip shadow stack protections instead of normal stack
sentinel, thus requiring special handling for this case. Just avoid this
test instead, if CONFIG_HW_SHADOW_STACK=y.

Signed-off-by: Ederson de Souza <ederson.desouza@intel.com>

Author: edersondisouza

tests/kernel/fatal/exception/src/main.c

@@ -385,7 +385,7 @@ ZTEST(fatal_exception, test_fatal)
 
 #ifndef CONFIG_ARCH_POSIX
 
-#ifdef CONFIG_STACK_SENTINEL
+#if defined(CONFIG_STACK_SENTINEL) && !defined(CONFIG_HW_SHADOW_STACK)
 	TC_PRINT("test stack sentinel overflow - timer irq\n");
 	check_stack_overflow(stack_sentinel_timer, 0);