Cleaned up working code that passes CI check for tv-casting test

Author: shaoltan-amazon

scripts/tests/run_tv_casting_test.py

@@ -190,11 +190,10 @@ def test_discovery_fn(tv_app_rel_path, tv_casting_app_rel_path):
         with LogFileManager(linux_tv_app_log_path, 'w') as linux_tv_app_log_file:
             tv_app_abs_path = os.path.abspath(tv_app_rel_path)
 
+            cmd = []
             if sys.platform == 'darwin' or sys.platform == 'linux':
                 # Try to avoid any stdout buffering in our tests.
                 cmd = ['stdbuf', '-o0', '-i0']
-            else:
-                cmd = []
 
             # Run the Linux tv-app subprocess.
             with ProcessManager(cmd + [tv_app_abs_path], stdout=subprocess.PIPE, stderr=subprocess.PIPE) as tv_app_process: