Merge #11965: qa: Note on test order in test_runner

fadf60e381 qa: Note on test order in test_runner (MarcoFalke)

Pull request description:

  C.f. #11964

Tree-SHA512: 5f087965093722d9e7a3febddcc187e412bd0636a7ed2da60111668fe3bba6668110e25a38ddcccc0d0aae132611c56fa72f3f0c473fb3fb59e38be445edfcd5

test/functional/test_runner.py

@@ -130,6 +130,8 @@ BASE_SCRIPTS= [
     'feature_logging.py',
     'node_network_limited.py',
     'conf_args.py',
+    # Don't append tests at the end to avoid merge conflicts
+    # Put them in a random line within the section that fits their approximate run-time
 ]
 
 EXTENDED_SCRIPTS = [