Add an experiment for the stream wait change (#2312)

To be a bit more cautious I think we should have an experiment for this new stream wait logic so that we can easily switch it on and off in prod, as well as being able to test it out with our own accounts first

packages/api/src/controllers/stream.ts

@@ -32,7 +32,10 @@ import {
   TooManyRequestsError,
   UnprocessableEntityError,
 } from "../store/errors";
-import { ensureExperimentSubject } from "../store/experiment-table";
+import {
+  ensureExperimentSubject,
+  isExperimentSubject,
+} from "../store/experiment-table";
 import messages from "../store/messages";
 import Queue from "../store/queue";
 import { DBSession } from "../store/session-table";
@@ -1257,8 +1260,12 @@ app.put(
       ? pathJoin(streamPullUrl + stream.playbackId, `index.m3u8`)
       : getHLSPlaybackUrl(ingest, stream);
     if (!stream.isActive || streamExisted) {
-      triggerCatalystPullStart(stream, playbackUrl);
-      await waitCatalystStreamReady(stream, playbackUrl);
+      if (await isExperimentSubject("stream-metadata-wait", req.user.id)) {
+        triggerCatalystPullStart(stream, playbackUrl);
+        await waitCatalystStreamReady(stream, playbackUrl);
+      } else {
+        await triggerCatalystPullStart(stream, playbackUrl);
+      }
     }
 
     res.status(streamExisted ? 200 : 201);