fixes for missing dependency tests (#1141)

AutomatedTesting/TestAssets/ReportOneMissingDependency.txt

@@ -0,0 +1,5 @@
+This is the UUID for libs / particles / milestone2particles . xml. 
+6BDE282B49C957F7B0714B26579BCA9A
+This isn an invalid UUID
+33bdee92F3225688ABEE534F6058593F
+This is another invalid UUID B076CDDC-14DK-50F4-A5E9-7518ABB3E851

Tools/LyTestTools/ly_test_tools/o3de/asset_processor.py

@@ -597,9 +597,10 @@ class AssetProcessor(object):
         run_result = subprocess.run(command, close_fds=True, timeout=timeout, capture_output=capture_output)
         output_list = None
         if capture_output:
-            output_list = run_result.stdout.splitlines()
             if decode:
-                output_list = [line.decode('utf-8') for line in output_list]
+                output_list = run_result.stdout.decode('utf-8').splitlines()
+            else:
+                output_list = run_result.stdout.splitlines()
 
         if run_result.returncode != 0:
             errorMessage = f"{command} returned error code: {run_result.returncode}"