test: add note about readable streams with type owning

PR-URL: #50779
Reviewed-By: Filip Skokan <panva.ip@gmail.com>
Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>

Author: MattiasBuelens

test/wpt/status/streams.json

@@ -24,6 +24,7 @@
   },
   "readable-streams/owning-type-message-port.any.js": {
     "fail": {
+      "note": "Readable streams with type owning are not yet supported",
       "expected": [
         "Transferred MessageChannel works as expected",
         "Second branch of owning ReadableStream tee should end up into errors with transfer only values"
@@ -35,6 +36,7 @@
   },
   "readable-streams/owning-type.any.js": {
     "fail": {
+      "note": "Readable streams with type owning are not yet supported",
       "expected": [
         "ReadableStream can be constructed with owning type",
         "ReadableStream of type owning should call start with a ReadableStreamDefaultController",