Add a configurable timeout around backend live feed startup

For now make it a larger value but ideally in the long run we can tune
it to specific backends and expose it in the config(s).

piker/data/feed.py

@@ -226,6 +226,7 @@ async def allocate_persistent_feed(
 
     loglevel: str,
     start_stream: bool = True,
+    init_timeout: float = 616,
 
     task_status: TaskStatus[FeedInit] = trio.TASK_STATUS_IGNORED,
 
@@ -267,22 +268,23 @@ async def allocate_persistent_feed(
     # TODO: probably make a struct msg type for this as well
     # since eventually we do want to have more efficient IPC..
     first_quote: dict[str, Any]
-    (
-        init_msgs,
-        first_quote,
-    ) = await bus.nursery.start(
-        partial(
-            mod.stream_quotes,
-            send_chan=send,
-            feed_is_live=feed_is_live,
+    with trio.fail_after(init_timeout):
+        (
+            init_msgs,
+            first_quote,
+        ) = await bus.nursery.start(
+            partial(
+                mod.stream_quotes,
+                send_chan=send,
+                feed_is_live=feed_is_live,
 
-            # NOTE / TODO: eventualy we may support providing more then
-            # one input here such that a datad daemon can multiplex
-            # multiple live feeds from one task, instead of getting
-            # a new request (and thus new task) for each subscription.
-            symbols=[symstr],
+                # NOTE / TODO: eventualy we may support providing more then
+                # one input here such that a datad daemon can multiplex
+                # multiple live feeds from one task, instead of getting
+                # a new request (and thus new task) for each subscription.
+                symbols=[symstr],
+            )
         )
-    )
 
     # TODO: this is indexed by symbol for now since we've planned (for
     # some time) to expect backends to handle single
@@ -908,6 +910,7 @@ async def open_feed(
 
                 for fqme, flume_msg in flumes_msg_dict.items():
                     flume = Flume.from_msg(flume_msg)
+
                     # assert flume.mkt.fqme == fqme
                     feed.flumes[fqme] = flume