tests: posix: threads_base: suppress SonarCloud false positives

Add NOSONAR annotations on intentional double-lock test cases:
- mutex.c: recursive mutex test that intentionally locks twice
- pthread.c: trylock failure test that intentionally attempts a
  second lock to verify trylock returns non-zero when already held

Signed-off-by: Seyoung Jeong <seyoungjeong@gmail.com>

Author: seyoungjeong

tests/subsys/portability/posix/threads_base/src/mutex.c

@@ -38,7 +38,7 @@ static void *normal_mutex_entry(void *p1)
 static void *recursive_mutex_entry(void *p1)
 {
 	zassert_false(pthread_mutex_lock(&mutex), "mutex is not taken");
-	zassert_false(pthread_mutex_lock(&mutex), "mutex is not taken 2nd time");
+	zassert_false(pthread_mutex_lock(&mutex), "mutex is not taken 2nd time"); /* NOSONAR */
 	TC_PRINT("recursive mutex lock is taken\n");
 	zassert_false(pthread_mutex_unlock(&mutex), "mutex is not unlocked");
 	zassert_false(pthread_mutex_unlock(&mutex), "mutex is not unlocked");

tests/subsys/portability/posix/threads_base/src/pthread.c

@@ -71,7 +71,7 @@ static void *thread_top_exec(void *p1)
 	 */
 	pthread_mutex_lock(&lock);
 
-	if (!pthread_mutex_trylock(&lock)) {
+	if (!pthread_mutex_trylock(&lock)) { /* NOSONAR */
 		printk("pthread_mutex_trylock inexplicably succeeded\n");
 		bounce_failed = 1;
 	}